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Why Are One in Two People Unfaithful?

You spent the whole day working from home in your little makeshift “office” (thanks, COVID-19!). The silence and loneliness are heavier today because your boyfriend had to go to the office (his real one), leaving you alone with the kitties. Your stomach growls. Dinner time is fast approaching. Your partner should be home in about half an hour, and you decide to surprise him by ordering a seafood pizza from the local pizzeria, your favorite take-out place. He’ll be so happy when he sees the famous pizza box on the counter after a long workday!

On your way out to the restaurant to pick it up, you grab his hoodie and pull it on. Plunging your hands into its pockets, you discover a small piece of paper with a phone number and a female name scribbled on it. You recognize neither. Doubts and questions start piling up in your head. Who is this person? Why didn’t he ever tell me about her? Is her phone number written on a piece of paper because he didn’t want to put it in his cell? Is he afraid that I’d find her in his contacts? Is he hiding something from me? Is he seeing her behind my back? Am I just being paranoid?


Although we rarely think that our partners will ever cheat on us – or vice versa, for those of us in committed relationships, infidelity is probably one of our worst nightmares. In early 2020, Club Sexu posted a survey on its social media, which was filled by 2,530 followers. According to its data, 57% of men, 57% of 🌈 people, and 48% of women reported having cheated on a partner at some point in their lives!

It’s hard to say whether Club Sexu’s followers are more – or less – unfaithful than other groups of people, since research findings on this topic vary widely. According to a review of 31 studies on infidelity, between 1% and 86% of respondents reported having cheated on their partner (Luo et al., 2010). This huge range is mainly due to the fact that no one has the same definition of infidelity!

What is infidelity?

Dans notre sondage maison, nous avions présenté une liste de comportements (présentée dans le tableau ci-dessous) en demandant au répondant ou à la répondante de sélectionner ceux qu’il ou elle percevait comme une infidélité.

In Club Sexu’s survey, a list of behaviours was presented to respondents, who were asked to select the ones they perceived as cheating (presented in Table 1). The results show that people were more likely to consider sexual behaviours, as opposed to affective or non-sexual types of behaviours, as infidelity. Our analyses also showed that men, 🌈 people, and people who have cheated on a partner before were generally less likely to consider any behavior on the list as cheating, compared to women and people who have never cheated.

It is also worth noting that no behaviour was perceived by 100% or 0% of people as infidelity, suggesting that there is no universal consensus on what counts as cheating.

This also means that it’s important for you and your partner to talk about what infidelity means to you at the very beginning of your relationship – whether you’re in a consensually monogamous or non-monogamous relationship – in order to make sure everyone’s on the same page. This conversation can definitely be a bit awkward, but it’s well worth it because it can help prevent misunderstandings and broken hearts in the future.

Table 1. “In your opinion, in a monogamous romantic relationship, what behaviour(s) count(s) as cheating?”

Behaviour% of participants who found that it “counts” as cheating
Liking “too many” pictures of another person  7.2%
Texting another person “too much”20.0%
Thinking a lot about someone else27.9%
Sharing a hotel room with another person32.7%
Thinking about someone else during sex39.1%
Dancing passionately with another person43.7%
Flirting with someone else46.6%
Kissing another person75.5%
Taking a shower with someone else81.8%
Sexting with another person82.5%
Petting or having oral with someone else88.7%
Having vaginal or anal sex with someone else88.5%

Why do people cheat on their partners?

We tend to think that people are unfaithful when they’re unhappy in their relationships or when partners are no longer compatible. In some cases, this is true and, according to several studies, this reason is reported by more women than men (Mark et al., 2011; Nicholls, 2008). But in reality, things are often more nuanced than that. Many of us cheat even when we’re satisfied with our relationships and in love with our partners.

For example, some of us develop a crush on a close friend (Halatsis & Christakis, 2009) or on our partner’s friend (Northup et al., 2013), whether or not we act on our feelings of attraction.

In other cases, some of us cheat on our partners because we’re searching for pieces of ourselves or exploring our identity (Perel, 2017). Sometimes, we find ourselves missing who we were 2, 5, or 10 years ago and we yearn to reconcile with this older identity. Or we can also become tired of the person we currently are and go in search of a new self. We tend to feel a little differently with each person we interact with, because each dynamic, friendship, and relationship is different. We might feel more adventurous when we’re hanging out with Carlos than with Jessica. When we’re with Fatma, maybe we feel more interesting and creative compared to when we’re in Theo’s company. 

And sometimes, many of us thrive on pursuing these self-discoveries. We become aware of our different “selves” and start cultivating identities – and therefore, relationships – that we enjoy, which are not always related to our current partner.

This very motivation – self-discovery and self-expansion – can be confusing to many of us, because it paints a reality that strongly contradicts our cultural beliefs about love and romance: that many people are unfaithful even when they are happy in their relationships.

This can be deeply unsettling and awaken many insecurities because it means our partners are unpredictable and that, sometimes, there’s nothing we can do to prevent them from cheating on us. But reassuringly, this motivation also implies that their infidelity had nothing to do with us.

So a person can be unfaithful because:

  • They experience sexual or relational dissatisfaction;
  • They have developed a sexual or romantic crush on a friend or a partner’s friend over time;
  • They are exploring themselves or are looking to reconnect with a former self.

Why is infidelity so painful?

Once discovered, infidelity is often experienced as a traumatic and destabilizing event because:

  • It brings up several fears and insecurities and raises important questions about our perceived value and that of our partners. It further makes us question the very nature of our relationship and the foundation it rests on. For example, “Did they cheat on me because I’m unattractive?”; “If he cheated on me, it means he’s a bad person.” ; “If she lied to me about that, what else is she lying to me about?” ; “Is our entire relationship based on lies?”
  • It is shrouded in lies and secrecy, which prevents us from fulfilling several basic needs such as the needs for transparency, authenticity, trust, intimacy, and predictability.
  • It confronts us with the fact that we don’t know as much about our partner as we thought. Because, culturally, we tend to define romantic relationships as rooted in  intimacy and mutual self-disclosure, a secret of this nature can be experienced as a personal offense or as a form of betrayal.

Can a relationship survive infidelity and grow stronger because of it?

Healing after infidelity is absolutely possible. However, it requires work on the part of both partners and not just the person who has been unfaithful.

Much of the work involves cultivating empathy and communicating your emotions and needs non-violently in order to better understand each other and find concrete solutions. For the person who has been unfaithful, empathy helps them better understand their partner’s pain as well as their needs for predictability, trust, and authentic connection. For the other person, empathy can help them see their partner’s infidelity not as an intentional betrayal or infliction of pain, but rather as an experience of closeness with another person or as an attempt to fulfill needs for identity, self-esteem, exploration, or connection.

It can be very difficult and even counterintuitive not to take a partner’s infidelity personally, but it is helpful to remember that it often has nothing to do with us and that, for example, wanting to experience a moment of intimacy with another person does not systematically mean that a partner has no desire to be intimate with us; these desires are not mutually exclusive.

Although infidelity can be an overwhelming experience, it offers potentially positive avenues by opening the door to:

  • An intimate and erotic wake-up call for one’s relationship
  • Better and more frequent communication, which in turn can lead to…
    • More closeness and emotional connection
    • A better or new understanding of one’s partner or oneself
    • Novelty between partners
    • The potential to renew passion
    • Reassess the nature of one’s relationship or relationship agreement

In short, infidelity does not systematically imply that a relationship is over. With the right tools such as honesty, transparency, and empathy, not only can a relationship “survive” an affair, but it can even come out stronger on the other side.

That said, prevention is better than cure: when we are unhappy in our relationships or desire to explore ourselves and connect with another person, it’s always better to talk about it with our partners. Suppressing this kind of thing can not only lead to resentment, but also to emotional distance between us and our partners and, you guessed it, to cheating.

Lastly, even if a relationship can survive an affair, reconciliation and the restoration of trust between partners is not always possible. Sometimes, ending the relationship is the best thing to do, and it’s up to each person to decide what’s best for them. #NoJudgmentHere


You wait, sitting in the kitchen, the pizza still in its box, slowly cooling on the counter. He’s late. It worries you and the doubts continue to multiply in your head.

You finally hear the front door open. Your partner puts down his bag and takes off his shoes. His face suddenly lights up when he sees the box bearing the logo of your favorite restaurant.

Yay! Oh my god, I’m so happy to see that – and you! It’s been a rough day. Felix left the company, and my boss transferred most of his projects to me. I’m not sure how I’ll manage. On top of all that, I just picked up my pants from the seamstress and she shortened them way too much!

What seamstress?

Her name’s Juliet. A friend recently recommended her to me.

Juliet. Sigh of relief.

The name on the piece of paper.  

  • Halatsis, P. et Christakis, N. (2009). The challenge of sexual attraction within heterosexuals’ cross-sex friendship. Journal of Social and Personal Relationships, 26(6-7), 919-937. https://doi.org/10.1177/0265407509345650

    Luo, S., Cartun, M. A. et Snider, A. G. (2010). Assessing extradyadic behavior: A review, a new measure, and two new models. Personality and Individual Differences, 49(3), 155-163. https://doi.org/10.1016/j.paid.2010.03.033 

    Mark, K. P., Janssen, E. et  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. https://doi.org/10.1007/s10508-011-9771-z 

    Nicholls, L. (2008). Putting the New View classification scheme to an empirical test. Feminism & Psychology, 18(4), 515-526. https://doi.org/10.1177/0959353508096180

    Northrup, C., Schwartz, P. et Witte, J. (2013). The normal bar: The surprising secrets of happy couples and what they reveal about creating a new normal in your relationship. Harmony.

    Perel, E. (2017) The state of affairs: Rethinking infidelity. Harper Collins.

    Rosenberg, M. (2015). Nonviolent Communication: A Language of Life. Puddle Dancer Press.