Why Happy People Cheat: The Hard Truth About Monogamy
Thursday, March 13, 2025.
Monogamy, for all its virtues, comes with a wildly misleading premise: If you’re happy, you won’t cheat.
This assumption has fueled self-help books, therapy sessions, and late-night tearful conversations over lukewarm coffee. It’s also completely wrong.
A massive study by Selterman et al. (2021) found that plenty of people in satisfying, loving relationships still cheat.
Not because their partner is failing them, but because they’re chasing novelty, self-exploration, or the fleeting thrill of being desired by someone new.
In other words, monogamy isn’t about happiness. It’s about values, impulse control, and how many chances you get to betray your partner without being caught.
The Great Lie: That Relationship Satisfaction Prevents Infidelity
For decades, we’ve told ourselves:
If your partner is loyal, they must be satisfied.
If someone cheats, it means they’re unfulfilled at home.
If you just “keep things exciting,” you can infidelity-proof your relationship.
But here’s the problem: The research says none of this is true.
Selterman et al. (2021) found that many cheaters reported being happy with their primary relationship. Their reasons for cheating had nothing to do with dissatisfaction and everything to do with:
✔ Novelty-seeking (“I just wanted something different.”)
✔ Self-discovery (“I felt like I was losing a part of myself.”)
✔ Ego validation (“It felt good to be wanted.”)
✔ Sheer opportunity (“One thing led to another, and here we are.”)
In fact, a disturbing number of participants openly admitted:
"I love my partner, I have no intention of leaving them, but I did it anyway."
Which raises a question no one wants to ask:
If happiness doesn’t stop people from cheating, what does?
The Four Real Reasons Happy People Cheat
If cheating isn’t just a symptom of relationship dissatisfaction, what else is driving it?
Novelty: The Brain Is a Hedonistic Junkie
Monogamy is great at providing stability, but absolutely terrible at providing novelty.
And the human brain? It loves novelty.
Dopamine, the brain chemical that fuels desire and motivation, spikes in response to new experiences—not necessarily deeper emotional connections (Fisher et al., 2006).
Long-term relationships naturally stabilize, which is good for emotional security but bad for sexual intrigue.
An affair, no matter how meaningless, triggers the brain’s reward system like a brand-new toy.
Or, to put it bluntly: It’s not about finding someone better—it’s about finding someone new.
Self-Exploration: The Affair as a Midlife Crisis in Action
A shocking number of affairs have nothing to do with the partner at all. They’re about the cheater’s own identity crisis.
Selterman et al. (2021) found that many people cheat because they want to reconnect with a version of themselves they feel they’ve lost.
The affair partner isn’t necessarily better than the spouse—they’re just different enough to make the cheater feel like a different person.
This explains why so many midlife affairs look like a cliché:
The suburban dad who suddenly has a fling with a younger coworker.
The devoted wife who falls for a reckless artist after decades of being the responsible one.
It’s not about love. It’s about reinvention.
Ego Boosting: The Cheap Thrill of Feeling Wanted
Some affairs have zero to do with dissatisfaction and everything to do with vanity.
People cheat because they want to feel desirable again—not because they don’t feel loved (Shackelford et al., 2008).
Many cheaters aren’t seeking a better partner—they’re seeking proof that they still "have it."
The affair provides a temporary self-esteem boost, even if the relationship itself is meaningless.
This explains why so many high-status men cheat—it’s not about love or even sex.
It’s about proof of dominance, attractiveness, and power.
Opportunity: The Bored, The Drunk, and The Unsupervised
If desire is the spark, opportunity is the gasoline.
Mark et al. (2011) found that many affairs aren’t premeditated—they happen because the conditions make it too easy to resist.
The key risk factors?
✔ Travel (Business trips are cheating wonderlands.)
✔ Alcohol (Because nothing good happens after the third drink.)
✔ Technology (Your high school ex just slid into your DMs.)
✔ Lack of accountability (What happens in Vegas stays in Vegas—until it doesn’t.)
This suggests that monogamy isn’t just about love—it’s about how many chances you get to cheat without consequences.
Which brings us to the real question at the heart of monogamy.
Monogamy Isn’t About Happiness—It’s About Self-Control
If happy people still cheat, then monogamy can’t just be about relationship satisfaction.
It has to be about something else entirely:
Impulse control.
Personal values.
Deliberate commitment.
Pronk et al. (2011) found that people with high self-regulation cheat far less than those who struggle with impulse control—regardless of how satisfied they are in their relationship.
Translation?
Monogamy is a choice, not a feeling.
People don’t stay faithful because they never feel tempted—they stay faithful because they decide to.
And for some, that decision is harder than others.
The Relationship Fix: How to Affair-Proof a Happy Marriage
If cheating isn’t always about relationship dissatisfaction, then “just make your partner happy” isn’t a great strategy for preventing infidelity.
Instead, the research suggests that strong couples:
✔ Acknowledge temptation rather than pretending it doesn’t exist.
✔ Keep novelty alive in the relationship instead of letting boredom win.
✔ Build a culture of validation and admiration so partners don’t seek it elsewhere.
✔ Create shared guardrails against opportunity (healthy boundaries, transparency).
In other words, don’t just assume your partner won’t cheat because they love you.
Make sure the relationship itself is a place where both of you feel fully alive.
Because if someone loses themselves in the relationship, they might just go looking for themselves somewhere else.
Love Isn’t What Prevents Cheating—Commitment Is
People want to believe that true love inoculates us against desire for anyone else.
But the science says otherwise.
Happy people still cheat.
Monogamy isn’t about eliminating temptation—it’s about resisting it.
Commitment isn’t about never wanting something new—it’s about choosing something lasting.
The real question isn’t "Do you love your partner?"
It’s "Will you still choose them when novelty, validation, and opportunity come knocking?"
Because love is a feeling—but fidelity is a choice. And therapists should be advocates for better choices.
Be Well, Stay Kind, and Godspeed.
REFERENCES:
Fisher, H. E., Aron, A., & Brown, L. L. (2006). Romantic love: An fMRI study of a neural mechanism for mate choice. Journal of Comparative Neurology, 493(1), 58–62.
Mark, K. P., Janssen, E., & Milhausen, R. R. (2011). Infidelity in heterosexual couples: Demographic, interpersonal, and personality-related predictors of extradyadic sex. Archives of Sexual Behavior, 40(5), 971–982.
Perel, E. (2017). The state of affairs: Rethinking infidelity. HarperCollins.
Selterman, D., Garcia, J. R., & Tsapelas, I. (2021). Why people cheat: A large-scale investigation of motivations for infidelity. Journal of Sex Research, 58(4), 512–526