Why People Who Love Their Partners Still Cheat (2024)

My colleagues and I recently published a study on romantic infidelity. We recruited a sample of individuals (mostly middle-aged, married heterosexual men) through Ashley Madison, a dating app for married people who are looking to cheat. The company's tagline is: “Life is short. Have an affair.” Just under 2,000 people participated in our study. They told us about their relationships with their spouses, their motivations, and how they felt about their affairs.

Past studies in this area found that when people had worse marriages (i.e., they indicated low relationship satisfaction or high conflict), they were more likely to have affairs compared to those whose relationships were better. But we did not find evidence for that in our samples. Overall, our participants rated their relationship quality as decent (not extremely high, obviously, but not very low either). In particular, our participants noted how much they felt love for their partners, and about a quarter of them said they did couples counseling to improve their relationships. The one thing that seemed to be lacking was sex. Half of our participants said they weren’t sexually active at all with their partners, and sexual dissatisfaction was a major motivation for our participants to seek affairs.

But among those who had affairs, their relationships did not get worse over time, nor did their psychological well-being. This is yet another result from previous studies that we could not find in ours. The participants who had affairs said they enjoyed them very much and felt little regret. This pattern was surprising in itself, considering that most people say that infidelity is morally wrong and a sign of a bad marriage. How can this be? And more generally, how can infidelity be so common if most people agree that it’s unethical?

I’ll give you a handful of uneasy thoughts to chew on, which may help explain this paradox.

1. People are complicated.
2. Monogamy is arduous.
3. Moral consistency may not truly exist in an objective sense.

People’s behavior often stems from underlying goals and motivations. We have goals for social connection, intimacy, and sex, along with goals for virtuousness, productivity, freedom, variety, and a lot more. But we can’t have everything we want in life, so difficult tradeoffs often result. The various goals we have may come into conflict with each other. People want to stay devoted to their spouses, who sometimes may be disinterested in sex (or disinterested in their partner’s body). Some may rather have an affair than dissolve a sexless or unexciting marriage, perhaps because they value the other aspects of their marriage with a lifelong partner. Sometimes spouses end up becoming closer friends over time, even as passion fades. In this sense, people may be making a moral tradeoff. Even as the average person disapproves of cheating, they may do so if they believe it’s the lesser of two evils.

As I wrote in a recent chapter for a psychology encyclopedia, some evolutionary theorists suggest that humans, like most animals, are not predisposed toward enthusiastically maintaining lifelong sexual exclusivity with one partner. In other words, monogamy can work for many people, but that doesn’t mean it’s enjoyable. It’s normal for people to desire others (romantically and/or sexually) throughout their lives. The challenge for us is how to contend with those feelings, and social norms often dictate how we do this. Some people attempt to repress those desires and internalize shame. Some engage with p*rnography. Some have open relationships. Some people cheat.

Depending on social and environmental conditions throughout the world, most societies fall somewhere in the middle of a “monogamy spectrum.” In many societies, some type of open relationship is not only normal, but actively encouraged. Knowing how common that is, it’s a bit peculiar that people anywhere would show such extreme distress toward an instance of infidelity. Not only do people strongly disapprove of their partners cheating on them, they also express moral condemnation toward others’ infidelities. People seem really bothered when other people are unfaithful to their spouses.

Fellow PT contributor Justin Lehmiller and I also noted in a separate book chapter that people often treat infidelity in absolutist terms—an ethical failure to be avoided at all costs. Scientists may have adopted this moralistic view as well. But we suggest more nuance. Infidelity can act as a stressor, which could result in negative, neutral, or even positive outcomes, depending on other variables, including personality traits, community norms, and other relationship factors.

Both exclusive and open relationships have strong ethical boundaries. Sometimes those boundaries are bent, and sometimes they are broken. But people often don’t stop to consider why those boundaries are set in the first place, what purpose they serve, and whether they actually strengthen or weaken relationships. Many people believe that having an agreement to be sexually exclusive with a partner will protect them from betrayal, but this is unwise considering how commonly infidelity happens, even in relationships that are happy and satisfying.

I suggest we have a healthy spirit of curiosity when thinking about relationship ethics. Instead of being reactive to the idea of others’ affairs, we should be genuinely inquisitive and responsive. We should try to understand why people behave the way they do, instead of just writing it off as sinful. People are more complicated (and more interesting) than merely “good” or “bad,” and there’s a lot more we have yet to learn about this fraught area of human experience.

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