By Stephanie Boucher, Registered Psychotherapist | The Mindful Loft
The short version: People often say narcissists cheat because of their need for validation, their lack of empathy, and their desire for control. There’s truth in that, and this article looks at what the research actually shows about narcissism and infidelity, which is more complicated than the popular story. But the word “narcissist” gets used so often now that it can muddy more than it clarifies. So alongside the research, this article holds onto something I keep coming back to in my work: whether your partner fits the label or not, your hurt is real, and you matter.
If you’re here, you’ve probably already used the word “narcissist” in your own head, or out loud, about someone you love. Maybe you’ve said it to a friend. Maybe you only let yourself think it late at night, after another conversation that left you feeling small, or after finding something you weren’t supposed to find.
For a lot of people, that’s exactly how they arrive at this question. Not in the abstract, but after a betrayal. Something came to light, and now you’re trying to fit two things together that won’t fit: the partner who can be so warm, and the partner who did this.
And underneath all of it, a quieter question: is something genuinely wrong in this relationship, or am I overreacting and making too much of it?
Let me start there, because it matters more than any definition. Whether or not a betrayal has happened, and whether or not your partner would ever meet a clinical definition, the confusion you feel is real. The sense of never quite being able to reach them, the way your own needs keep ending up at the bottom of the pile, the feeling that you have to choose between being honest and keeping the peace. Those experiences are real on their own terms. They don’t need a diagnosis to be valid. We’ll get to the research on narcissism and infidelity, because it’s genuinely interesting. But I want to be honest with you from the start about what actually matters here.
A word about the word “narcissist”
These days, the word is everywhere. People call their exes narcissists, their bosses narcissists, their in-laws narcissists. Sometimes it fits. Often it’s reaching for the strongest word available to describe a real hurt. But someone can be genuinely selfish, dismissive, or hard to reach without being narcissistic at all. Plenty of painful behaviour isn’t narcissism. It’s immaturity, avoidance, stress, self-protection, or simply someone who has never learned to show up well for another person.
I want to slow the word down a little. In my work, when someone tells me their partner is a narcissist, what they’re usually describing is a partner who seems self-absorbed, who struggles to show empathy, and who, when they do try to be understanding, somehow misses the mark or makes it feel performed rather than genuinely felt. That experience is real and worth taking seriously, whatever the correct label turns out to be.
Here’s the thing I find myself saying, gently, in the room: whether your partner meets the clinical definition of narcissism is almost beside the point. The thing I’m certain of is that the person in front of me is suffering, is not feeling seen, and has gotten very good at putting their own needs last. That’s the part that’s real. That’s the part we work with.
So if you take nothing else from this article, take that. You don’t have to be right about the label in order to deserve to be treated well. Most people in your position aren’t trying to get their partner formally diagnosed. They’re trying to name something that’s been hurting them for a long time. The label is a tool for that, and like any tool, it’s useful only as long as it helps you see your situation more clearly, not less.
What narcissism actually is
It helps to know what the word means clinically, so you can use it with more precision and less self-doubt.
Narcissistic Personality Disorder is a specific, diagnosable condition. According to the most current edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5-TR), it involves a long-standing pattern of grandiosity, a deep need for admiration, and a lack of empathy. Estimates of how common it is vary quite a bit depending on how it’s measured. A large US epidemiological study (Stinson et al., 2008) put the lifetime prevalence around 6%, while other reviews land closer to 1%, and it’s diagnosed more often in men. The point is that the full clinical disorder is far less common than the casual, everyday use of the word would suggest.
Narcissistic traits, on the other hand, exist on a spectrum, and all of us have some. Someone can be self-centered, validation-hungry, or emotionally unavailable without meeting the criteria for the disorder. This distinction matters, because the partner you’re thinking about may have real narcissistic traits that genuinely hurt you, without being a textbook case of the disorder. Both can be true. Both can be painful.
What the research really says about narcissism and cheating
Here is where the popular story and the actual evidence start to diverge.
The popular story goes like this: narcissists need constant validation, lack empathy, and crave control, so they’re far more likely to cheat. There’s a kernel of truth in it. The traits that come with narcissism, entitlement, a hunger for admiration, a tendency to see relationships as a way to get one’s own needs met, can absolutely set the stage for betrayal.
But the research is messier than that tidy story suggests.
When researchers study the so-called “Dark Triad” of personality traits (narcissism, Machiavellianism, and psychopathy) and their link to infidelity, narcissism turns out to be a less consistent predictor of actual cheating than people assume. Across studies, narcissism tends to predict a greater willingness to cheat more reliably than it predicts actually doing it.
In plainer terms: having narcissistic traits seems to make someone more open to the idea of cheating, but it doesn’t mean they will, and it’s not the trait most tied to actually following through. Across this body of work, the trait most consistently linked to actual cheating is psychopathy, which involves a deeper coldness and lack of remorse than narcissism alone.
There’s another layer worth knowing. A 2023 study in the journal Sexual and Relationship Therapy found that narcissism predicted emotional infidelity, while psychopathy predicted both physical and emotional infidelity. In other words, the kind of betrayal narcissism is most linked to may be the emotional affair, the secret closeness with someone else, rather than the purely physical kind. The researchers suggested that older, contradictory findings came from lumping all cheating together, when emotional affairs, physical affairs, and other types actually behave differently.
What does all this mean for you, sitting with a partner you suspect has betrayed you? A few honest takeaways:
- The link between narcissism and cheating is real but not simple. Narcissistic traits raise willingness and entitlement around betrayal, but they don’t make cheating inevitable, and they’re not the strongest predictor of it.
- Plenty of people with narcissistic traits never cheat. And plenty of people who cheat aren’t narcissists.
- Which loops back to the point I keep returning to: the label is less useful than the pattern you’re actually living.
Why betrayal can feel more devastating with a narcissistic partner
Even though narcissism doesn’t reliably predict cheating, there’s a reason betrayal by a partner with strong narcissistic traits can feel uniquely shattering.
It’s the whiplash. In my work, what I hear described again and again is the experience of a partner who could be warm, attentive, even adoring in one moment, and cold, dismissive, or secretive the next. When the betrayal comes to light, it doesn’t just hurt. It scrambles your sense of what was real. You find yourself replaying the good moments, wondering if they were ever true, questioning your own memory and judgment.
Many people also describe a particular and painful shift after the betrayal comes out: a partner who had been warm and loving suddenly turning cold, defensive, or even hostile. Instead of the remorse you expected, you get distance. This is something clinicians who work with narcissism, including Wendy Behary, have noted. The coldness after discovery can feel like a second betrayal on top of the first, and it leaves many people more confused than ever about who their partner really is.
This is part of why people in this situation so often say some version of “I feel like I’m going crazy.” You’re not. You’re trying to hold two irreconcilable pictures of the same person at once, and that’s genuinely disorienting. The secrecy and the mixed signals do that to a nervous system. It’s not a character flaw in you. It’s what happens when the person who’s supposed to be your safe place is also the source of the threat.
The therapist Wendy Behary, who has spent decades working with narcissism, describes the way the warm, charming surface often sits on top of a deeply fragile sense of self. In her book Disarming the Narcissist, she frames much of the difficult behaviour as a defense protecting an inner world the person can’t bear to look at. That doesn’t excuse the betrayal. But it can help explain why the person who hurt you can seem so confident and so brittle at the same time. Put simply: the bigger the front someone puts up, the more they may be protecting something fragile underneath. That doesn’t make their choices your responsibility, and it doesn’t mean you have to stay and absorb the fallout. It’s just context that can make the confusing behaviour a little less crazy-making to live with.
Do narcissists feel guilt about cheating?
This is one of the most common questions I hear, and the honest answer is: it depends, and often less than you’d hope.
Genuine remorse requires being able to see your own part in causing someone else pain, and to sit with the discomfort of that. For someone high in narcissistic traits, that kind of self-reflection is genuinely hard, because it threatens the image they need to maintain of themselves. In my experience, it can be almost unbearable for them to sit with the agony of their own flaw, even for a second, because letting it in feels like it would shatter the whole picture they hold of who they are. So instead of staying with the discomfort long enough to feel real remorse, they push it away fast. You may see apologies that feel hollow, or that quickly turn into blame (“if you’d paid more attention to me, this wouldn’t have happened”). You may see them seem more upset about being caught than about the hurt they caused.
If you’ve waited for an apology that actually lands, and it never quite comes, this is often why. It’s painful. And it’s not a sign that you’re asking for too much.
Will a narcissist change?
People will tell you a narcissist will never change. I’ll be honest about where I land on this, because I think you deserve honesty rather than a slogan.
I don’t actually believe “never” is true. People can change, including people with narcissistic traits. But I won’t pretend it’s common or easy. Narcissism is widely considered one of the harder patterns to shift in therapy, in large part because meaningful change requires exactly the thing the traits work against: the willingness to look honestly at yourself and to sit with discomfort instead of defending against it. Many people with strong narcissistic traits never enter therapy at all, or leave when the work starts to touch something tender. So while “never” isn’t quite accurate, I completely understand why it feels true to so many people who’ve waited years for a change that didn’t come.
What this means for you is that hope isn’t foolish, but it should be grounded in what you’re actually seeing, not in what you’re hoping to see.
How do you know when you’re ready to leave?
I can’t tell you whether to stay or go. No one can, and anyone who claims they can after reading one article doesn’t understand how personal this is.
But here’s the frame I come back to. In my experience, people become ready to leave when the defeat outweighs the hope. Picture an old set of scales. On one side, the hope: the moments of connection, the progress you think you see, the future you imagined. On the other side, the defeat: the repeated hurts, the apologies that don’t land, the slow erosion of your sense of yourself.
When infidelity is part of the picture, it tends to land heavily on the defeat side, and not only because of the betrayal itself. It’s the aftermath that often tips the scale: whether your partner can sit with the hurt they caused, whether the remorse feels real, whether the behaviour actually changes or just the promises do. One affair, fully owned and genuinely repaired, weighs differently than an affair that’s minimized, blamed on you, or quietly repeated. You’re not just weighing the cheating. You’re weighing what happened after.
It’s not my job, or anyone’s, to tell you which side is heavier. Some people watch their partner do real work and the hope side gains genuine weight. Others keep getting hurt and the defeat side keeps growing until it tips. Only you can feel which way your own scale is leaning. Your job isn’t to make the “right” decision today. It’s to keep paying honest attention to which way it’s tipping, and to stop pretending the defeat side is lighter than it is.
Protecting yourself while you figure it out
Whatever you decide, you can start protecting your own wellbeing now:
- Trust what you notice. If something repeatedly feels off, that pattern is data. You don’t need to talk yourself out of it.
- Stop trying to win the diagnosis debate. You don’t need your partner to admit they’re a narcissist, or to prove it to anyone, in order to act on your own needs. Be prepared for the possibility that they turn it around and accuse you of being the narcissist. This happens often, sometimes as genuine confusion, sometimes as a defense to deflect attention. Either way, getting pulled into proving who is and isn’t the narcissist is usually a dead end. You can step out of that argument and still take your own experience seriously.
- Reconnect with people outside the relationship. Isolation makes the confusion worse. Steady friends, family, or a therapist can help you trust your own perceptions again.
- Start putting one of your own needs back near the top of the pile. Not all of them at once. Just one, as practice. You’ve likely spent a long time putting yourself last.
When you’re ready
If you’re carrying the aftermath of betrayal, by a partner with narcissistic traits or otherwise, you don’t have to sort through it alone. I offer a free 20-minute consultation. No pressure. Just a conversation about where you are and whether one of our therapists is right for what you need.
If the betrayal has left you feeling like you can’t trust your own mind, you may find our article on why infidelity can feel like PTSD helpful. And if you’re trying to make sense of what does and doesn’t count as betrayal in the first place, this piece on what counts as cheating may be a useful next read.
Not ready to book? I write about this territory monthly in our newsletter, The Messy Loft. Subscribe for free for thoughtful reflections on relationships, repair, and understanding yourself more clearly. We really are in this mess together. Read or subscribe to The Messy Loft
Frequently asked questions about narcissism and infidelity
Are narcissists more likely to cheat?
The honest answer is: somewhat, but it’s complicated. Narcissistic traits are linked to a greater willingness to cheat and a sense of entitlement that can justify it, but research finds narcissism is not the strongest predictor of actually cheating, and many people with narcissistic traits never do. The popular “narcissists always cheat” story oversimplifies what the evidence shows.
Do narcissists know they’re cheating and that it’s wrong?
Generally yes, they know. The harder question is whether they feel the weight of it the way a partner would hope. Because genuine remorse requires self-reflection that’s difficult for someone high in narcissistic traits, the wrongness often doesn’t land the way it would for someone else.
Do narcissists feel guilty after cheating?
Often less than you’d want. You may see apologies that feel performed, or that shift into blame, or more distress about being caught than about the hurt caused. If the remorse you’ve been waiting for never quite arrives, this is frequently why.
Will a narcissist cheat again?
There’s no guarantee either way, but if the underlying patterns (entitlement, lack of genuine remorse, difficulty with self-reflection) haven’t changed, the risk remains. Change is possible but rare, and it depends on real, sustained self-awareness rather than promises made in the moment.
Is my partner a narcissist, or am I overreacting?
You may never get a clinical answer, and you don’t need one. What you can pay attention to is the pattern: do you consistently feel unseen, dismissed, and like your needs come last? That experience is valid and worth acting on, regardless of whether your partner would ever meet a formal diagnosis.
Does cheating mean my partner is definitely a narcissist?
No. Infidelity is far more common than narcissism and has many causes. As Esther Perel writes, many people who cheat aren’t trying to hurt their partner but are wrestling with unmet needs, unresolved grief, or a longing for connection. Cheating is a serious betrayal regardless, but it isn’t proof of narcissism.
Further reading
These are accessible, general-audience reads if you want to go deeper:
- Wendy Behary, Disarming the Narcissist. A clinician’s practical guide to understanding narcissistic patterns and protecting yourself within them. The most recent edition adds material on shame and infidelity specifically.
- Dr. Ramani Durvasula, Should I Stay or Should I Go? Surviving a Relationship with a Narcissist. A practical, plain-language guide from a clinician who specializes in narcissistic relationships.
- Esther Perel, The State of Affairs: Rethinking Infidelity. A thoughtful, very readable look at why affairs happen and what they mean, including for people whose partners aren’t narcissists at all.
References
American Psychiatric Association. (2022). Diagnostic and statistical manual of mental disorders (5th ed., text rev.).
Behary, W. T. (2021). Disarming the narcissist: Surviving and thriving with the self-absorbed (3rd ed.). New Harbinger.
Stinson, F. S., et al. (2008). Prevalence, correlates, disability, and comorbidity of DSM-IV narcissistic personality disorder. Journal of Clinical Psychiatry, 69(7), 1033-1045.
Perel, E. (2017). The state of affairs: Rethinking infidelity. Harper.
Recent research on Dark Triad traits and infidelity, including findings from Sexual and Relationship Therapy (2023) that narcissism predicts emotional infidelity while psychopathy predicts both physical and emotional infidelity.
This article is for educational purposes and is not a substitute for individualized mental health care.
If you are in immediate crisis or thinking of harming yourself, please reach out to a crisis line in your area. In Canada, you can call or text 9-8-8.
