If you’re wondering “why do people cheat” you’re asking the wrong question, and you may be coming from an overly idealistic point of view.

The real question is why are people faithful.

This article shows you the key psychological drivers for extra-pair sexual interest and the psychology of cheating.

But first, an overview:

Psychology of Cheating

People cheat because they had the opportunity to, and because evolution programmed them to take advantage of that opportunity.

This is true for any personality type.
From avoidants to dark triads who are most likely to cheat to ‘good guys and nice girls’ who may have lower intentions to cheat.

The Science of Infidelity

From a general point of view, cheating increases payoff in any cooperative relationship.
As The Oxford Handbook of Psychology:

the greater net individual benefit of defecting in a trust game (i.e. , when one partner cheats but the other does not) suggests that human’s evolved mating psychology is configured to motivate calculated deception (i.e. , infidelity) 

And more specifically for relationship infidelity, cheating is adaptive and inborn.
Both men and women are ‘programmed’ with the possibility of cheating, as Harrison writes in the Cambridge Handbook of Female Sexual Adaptations:

Since our brains process information in a manner to facilitate adaptive behavior (Cosmides & Tooby, 1987), it seems that selection favored at least some degree of extra-pair sex (Andrews et al., 2008)

Both men and women cheat because cheating can provide reproductive advantages.

For men, cheating can spread our genes wider and can help them produce better offspring or both.

And for women, it can provide superior genetic offspring from a higher mate value man, or at least increase genetic diversity for her offspring.

Cheating is indeed relatively common, and a human universal.
And you don’t usually reach a wide “adoption rate” despite the heavy risks, unless it provides a genetic advantage.

Now for the really complex, this article explains what factors increases and psychological traits increase the odds of cheating.

External Factors

A few factors are independent of personality, values, and morality.

These factors don’t “force” anyone to betray, but they increase the likelihood of cheating for everyone.
Here are some of them:

#1. Lifestyles of Cheating Opportunities

Professions and lifestyles that require lots of time away from our partners, for example:

• Regular travels
• Conferences attendance
• Military personnel on far away basis
• Nomadic lifestyles
• Long distance relationships

For most people, the workplace with its daily interactions and increased female participation, has been the main driver of the increase in infidelity in the last decades (Shirley Glass, 2004).
Road warriors and conferences, with alcohol mingling and hotel rooms readily available also lower the bar for cheating.

Example:
The movie Up In The Air is such an example:

#2. Libertine Social Environments

We are social creatures and we have a strong tendency to accept the values that our society and social groups embrace.

And also a rather strong tendency to act along the social-sanctioned rules.

A study in the Netherlands confirmed indeed that the sanctions -or lack thereof- from the group predicted the willingness to engage in extramarital affairs.

That means that if we have many friends who cheat, we are much more likely to cheat. If our friends don’t cheat, or if grew up in an environment where cheating is highly sanctioned, cheating is much rarer.

Traits of Cheating Partners

As much as there are traits that increase the odds of finding a loyal man or woman, there are also traits that have been shown to correlate with infidelity.

• Extroversion
• Sensation seeking (Lalasz & Weigel, 2011)
• Poor impulse control (Brady et al. 2020)
• High sexual permissiveness & Unrestricted sociosexuality (Barta & Kiene, 2005; Rodrigues et al. , 2017)
• Avoidant attachment style (DeWall et al., 2011)

Family Influences

How we grew up has a huge influence on how we are. Including how we are when it comes to fidelity.

#1. Like Father, Like Son

Studies show that affairs and cheating are more likely to occur among individuals who have a history of affairs in their own family (Emily Brown, Patterns of Infidelity).

And the correlation is quite huge: Bonnie Eaker Weil recorded the data in her clinical experience and found out that 90% of unfaithful patients had at least one unfaithful parent (Bonnie E. Weil, Adultery: The Forgivable Sin).

#2. Parents’ Bad Influences

Some influences are unconscious, deeper, or darker:

• Uncaring parents

Some parents are very hands-off and give their children all the freedom they want. Some children can take it as a sign of neglect.
If their partners also grant them all the freedom, they might act out more and more to get reprimanded -a sign of caring-.
Eventually, they might end up cheating as their ultimate effort to get a sign of love.

• I won’t be cheated on: strike first

Sometimes a woman who sees a womanizing father make her mother suffer might vow, consciously or subconsciously, to never be like her mother.
This means she’ll be like her cheating father…

• I won’t be dependent like dad

If we see a parent who is stuck in a terrible marriage they have little control over, we might subconsciously avoid any strong ties.
Cheating then becomes a way to assert our distance and independence.

• Childhood abuse

Men or women who were sexually abused during childhood may engage in compulsive sexual behavior. It goes for both men and women (Carol Rinkleib Ellison, 2000).
The movie Mysterious Skin is a good example but it’s too heavy and I won’t post it here.

• Emotional incests

Some father snubs their wives and showers their daughters with gifts and attention (Patricia Love, The Emotional Incest Syndrome).
Some other times the daughter sees the father giving all the attention to a lover and not to her mother.
These girls develop the unconscious desire of being the other woman and go after married men.

• The caretaker

Some children grow up in an environment that forces them to take care of several members of their family. They give, give, give, and take little or nothing.
Most of the time, it’s women.
These women tend to get stuck with cheating men who give them very little in return.

Relationship Phases

Some transitions can create discomfort and require some adjustments.

The more the couple has difficulties readjusting, the more cheating is likely to happen.
These are the major phases:

#1. Resisting Commitment (young relationship)

The couple hasn’t fully tested yet their compatibility.

If they were wrong and living together proves difficult, partners can start being more open to extramarital affairs.
And of course, some partners can find solace in cheating when they are afraid of commitment. Cheating then becomes a sort of escapism.

#2. Run Before It’s Too Late (pregnancy)

The man can feel he’s about to get trapped for good when the woman is pregnant. Cheating at this point is a way to break free and re-assert his freedom.

#3. Baby-Envy (parenthood)

The baby usually gets the lion’s share of the woman’s attention when he comes into this world. And hormonal changes happen.
Here are some common issues:

• Some men are less attracted to their women (see Madonna/Whore complex)
• Many women have less sex drive after a baby
• Some men are jealous of the mother/baby bond and feel left out

#4. Respite Cheating (turbulent teens)

When children become teenagers the household can experience some turbulent times, and marital satisfaction is often at its lowest during this period.
Cheating and having an affair can provide some respite. Also, some mothers can be reminded of their sexual yearnings by their own children.

#5. Should I Also Go (launching)

When children leave home, another critical phase rushes in.
Couples who experienced friction with their children can experience a re-blooming of their relationship.
But child-centered relationships are where children the glue can come apart. Or stay together while looking for outside sources of pleasure.

#6. I Can Still Do It (retirement)

Retirement is another major adjustment period. Some can feel a pang of meaningless, wondering if there’s nothing more to live for. And an affair can give life the sparkle.
For some others, especially men, it serves to prove they are still young enough to find a mate.

Personal Troubles

As much as the relationship goes through phases, so do the people in those relationships. Cheating is more likely to happen during these phases.

#1. I’ve Changed… And You?

Sometimes we evolve, but our partner stays the same.
That’s when cheating with a partner who is more like we are becoming is more likely to happen.
Some other times it’s not about how we are becoming but how we would like to be.

Example:
We don’t know if Mrs. Doubtfire cheated, but it’s a typical example where an affair is likely to happen because of how apart the couple grew:

#2. Midlife Crisis

Midlife crisis can bring a host of issues, including:

• Existential crisis: is this all there is?
• Parents’ death: are we next? Am I doing the best I can do?
• Am I still young enough? A younger mate can prove that
• Comfort level: not much more to strive for

Example:
The lovely movie Lost in Translation is an example of an affair during middle life crisis:

#3. Attachment Styles

Here’s a quick lowdown:

Secure attachment types tend to have one relationship at a time, create a strong and solid emotional bond, and tend to cheat less. The monogamous types we talked about in signs your partner is cheating are usually secure attachment types.

Anxious attachment types crave emotional closeness but are always afraid their partner might not feel the same.
They often end up in a relationship with the avoidant types (Amir Levine, Attached), which makes them feel starved for affection. They might cheat to get the emotional intimacy they crave, and they get attached very quickly to the affair partner.

Avoidant attachment types are fearful of emotional intimacy. For these types, an affair provides a way to get more autonomy, and research proves avoidant cheat the most: twice as much as all the other attachment types. And they are more likely to cheat multiple times and have more one-night stands (Allen, Baucon, 2004).

Example:
Mastroianni in La Dolce Vita is a great example of a cheater-avoidant attachment type

Relationship Issues

Cheating can be the consequence of troubles in the relationship. And when you can fix those relationship issues, you can also lower the chances (and the need) for cheating.

#1. Cheating to Escape

Sometimes life in the relationship can become a grey doldrums. And sometimes it can be straight-up painful.

Imagine having to attend to a sick parent or a child who’s had an accident.
These tragic occurrences can take a huge toll on the couple. Cheating can be a way to escape emotional pain: the lover is the antidepressant.

#2. Power Struggles: Cheating to Get Even

Some spouses can feel smothered under the tight grip of their more powerful partner. Cheating can be a way to get back at him and get even.

And of course, the most popular cheating is revenge against having been cheated.

#3. Loneliness: Cheating for Emotional Starvation

Some couples spend years or even decades without ever really getting to know each other.

When they finally meet someone who listens, asks questions, and wants to know their fears and dreams, then they are liable to fall for them hard.

Example:
There are many examples in movies, but I like The Good Girl which is basically all about emotional cheating:

You fix this issue by asking questions, listening empathically, and getting to know your partner. And by learning emotional intelligence and emotionally tuning in to your partner.

#4. Child-centered Relationships

Some relationships put children above everything else.
That also means though that there’s no space for romance between the spouses.
And when there’s no romance at home, partners look for it outside.

#5. So Bad There’s No Escape

Sometimes people cheat at the end of the umpteenth terrible argument, or when they just can’t take it anymore and they deeply want to move on.
They can cheat as a way to “force themselves” out of the relationship or to officialize that it’s over.