Why Do People In Happy Relationships Cheat?

By Dr. Justin Relationships : people who don’t feel sexually fulfilled are more prone to infidelity

Take a moment to picture a married person having an affair. Now, think about what their story is. Why is this person cheating? Chances are that the narrative you came up with involves someone who is dissatisfied with their relationship in some way. Perhaps they fell out of love. Maybe they were in a sexless marriage. Or perhaps they felt angry, neglected, or even bored with their partner. These are certainly all common factors that people who have committed infidelity often point toward. And that makes sense. After all, we know that infidelity has the potential to blow up a relationship (indeed, it’s one of the leading causes of divorce). So why would someone take this enormous risk that could potentially end the relationship unless they were already thinking about leaving?

Although this explanation makes intuitive sense, it only scratches the surface when it comes to understanding infidelity. Cheating can also pop up in relationships that would appear to be perfectly happy and healthy. Perhaps not surprisingly, these affairs can be amongst the most painful discoveries. I mean, imagine you’re in a dream relationship where you feel safe and connected—and you’re having amazing sex, too. But you find out your partner has cheated anyway. This can rock a secure attachment to its very core and leave you questioning everything.

So why do people in happy relationships sometimes cheat? Let’s explore.

speak with a certified sex and relationship therapist to dive into the root cause

The Third Variable Problem

Historically, studies that have looked at sexual satisfaction in relation to cheating have pointed to a singular conclusion: people who don’t feel sexually fulfilled are more prone to infidelity. More recent research, however, points to a non-linear association, meaning that people at both low and high levels of sexual satisfaction are the ones cheating the most. If the sex is great, though, why look elsewhere? It might be because high sexual satisfaction is a marker for some other trait or characteristic that predisposes people to cheating. For example, one of the prime candidates here would be having a sensation-seeking personality, which basically means you get off on having more thrilling sexual encounters. Being in a relationship with a sensation seeker can lead you to have a more passionate sex life together because your partner enjoys constantly trying new, different, and exciting things with you in the bedroom (and beyond). For example, they might propose sneaking away for a “quickie” while you’re at a party. Or they might indulge your wildest fantasy.  Sounds hot, right? However, your partner’s underlying impulsivity, while it might lead to some super intense and passionate encounters together, is a double-edged sword. That same impulsivity might make it harder for them to resist temptation when other opportunities arise, such as when an attractive stranger chats them up at a bar while they’re alone on a work trip. Research finds that sensation-seeking is indeed associated with greater odds of infidelity. And there lies the problem—a third variable (sensation seeking) can simultaneously lead to great sex within the relationship while also opening the door to starting affairs.

Infidelity can also be a product of something much deeper, a crisis of identity or a search for the self.

A Search For The Self

In order to fully understand why people in happy relationships cheat, we need to look beyond the third variable problem. Infidelity can also be a product of something much deeper, specifically, a crisis of identity or a search for the self. As sex therapist Esther Perel explains in her book The State of Affairs, happily married folks who commit infidelity sometimes do so as part of a process of self-discovery. For example, in very long-term relationships, people sometimes feel as though they have “lost themselves” in their relationships, perhaps because they gave up hobbies or other interests they once had that their partner didn’t share. This can lead to a drive for some degree of personal autonomy or freedom—the ability to make some of your own choices independently. Supporting Perel’s assertion, research has found that seeking autonomy is one of the more common reasons people cheat. Related to this, people in LTRs, especially those who settled into relationships at a very young age, sometimes find themselves engaging in what social psychologists refer to as “counterfactual thinking.” This involves pondering “what might have been.” In other words, how might your life be different if you had made different choices or taken another path? Frequent thinking along these lines can prompt some anxiety or even existential worry. What else is out there that I haven’t explored or that I might never have the chance to explore before it’s too late?’

Yes, it’s a cliché, but the “mid-life crisis” is real. You might very well have a loving spouse, a great family, a successful career, and all of the other things that are supposed to make us content in life. But that doesn’t make us immune from thinking about the “what ifs.” For instance, what if you broke the rules once in your life? I’ve spoken to many sex and relationship therapists who have told me stories about clients who, by all appearances, seemed to be in model marriages—but there was some underlying anxiety that they ended up coping with in a self-destructive way, such as by having an affair.

common narratives of dissatisfaction, complexities and motivations of cheating

What It All Means

What all of this tells us is that we need to challenge some of our assumptions about infidelity. Cheating does not always spring from “broken” or unhappy relationships. And at the same time, being in a great relationship doesn’t necessarily ensure that infidelity will never emerge. This doesn’t mean that cheating is inevitable or that if you’re in a great relationship, you should suddenly start worrying that your partner is secretly having an affair. None of this is to excuse or rationalize away cheating either. Instead, the take-home here is that, in addition to continually working on our relationships, we also need to be working on ourselves. For example, suppose you’re the impulsive type who finds it hard to resist temptation. In that case, the answer might reside in making a concerted effort to avoid putting yourself in situations where opportunities and temptations to cheat might arise. It’s usually easier to avoid a tempting situation altogether than it is to extract yourself from one in the heat of the moment. Alternatively, if you find yourself having one of those identity crises or anxiety is starting to bubble up, it might be time to speak with a certified sex and relationship therapist to dive into the root cause and find a productive way of resolving it. By continuously working on ourselves, we have an opportunity to pull back well before we get to the brink of a potential relationship disaster.


Lalasz, C. B., & Weigel, D. J. (2011). Understanding the relationship between gender and extradyadic relations: The mediating role of sensation seeking on intentions to engage in sexual infidelity. Personality and individual differences, 50(7), 1079-1083.

Lehmiller, J. J. (2023). The psychology of human sexuality. John Wiley & Sons.

Perel, E. (2017). The state of affairs: Rethinking infidelity-A book for anyone who has ever loved. Hachette.

Selterman, D., Joel, S., & Dale, V. (2023). No Remorse: Sexual Infidelity Is Not Clearly Linked with Relationship Satisfaction or Well-Being in Ashley Madison Users. Archives of sexual behavior, 1-13.

Selterman, D., Garcia, J. R., & Tsapelas, I. (2019). Motivations for extradyadic infidelity revisited. The Journal of Sex Research, 56(3), 273-286.