Why Guys Cheat

To be honest, both men and women cheat. But with that said, men are more likely than women to cheat and there are some important differences between the sexes when it comes to cheating.

In order to understand why men cheat, it helps to understand what causes both men and women to be unfaithful.
Why do both men and women cheat?

The science of cheating is very clear on this point: Roughly 3% of all mammals, including humans, practice what is called pair bonding or monogamous mating. However, even within the 3% of mammals that practice monogamy, very few species, including humans, are truly monogamous. In fact, when it comes to both men and women, monogamy is not our natural sexual strategy.

To make a long story short, for millions of years, the desire to mate with multiple partners was a very useful reproductive strategy. Men and women, who cheated on a partner, were more likely to succeed at having more children than people who were completely faithful to a mate. Cheating was a strategy to increase reproductive success and diversify risk. Or think about it this way: investing in a mutual fund (multiple stocks) is, on average, a better financial strategy than putting all of your resources into a single stock. Because cheating was a better reproductive strategy than monogamy, all of the men and women who are alive today are the descendants of people, who for millions of years had the propensity or the desire to cheat on a partner. Simply put, we have inherited this trait from our ancestors – it is a part of our human nature. This does not mean that everyone will cheat on a partner or that people are fully aware of their unconscious sexual desires. For a more detailed discussion on the nature of cheating, please see why people cheat.
How are men and women different when it comes to cheating?

While both men and women cheat, there are important sex differences when it comes to cheating. The sex differences that influence cheating are based on two basic biological differences between men and women.

First, men and women differ when it comes to eggs and sperm. Men can produce hundreds of millions of sperm per day. By comparison, women are born with a million or so eggs, but only a fraction, roughly one egg released every 28 days over a short period of time - from puberty to menopause - has the potential to create life. Simply stated, women have about 400 viable eggs to use (and taking into account gestation, only about 20 actual opportunities to reproduce), while men are capable of producing billions and billions of sperm.

The second basic biological difference deals with gestation. Embryos grow and develop in women, not men. For men, reproduction can literally take just a few minutes of effort; while for women it involves, at the very least, a nine-month process.

From a biological point of view, men can constantly and quickly engage in reproduction while women are much more limited in their ability to do so.

These biological differences influenced our psychological desires before the invention of modern forms of birth control and still influence our unconscious sexual desires today. Men are more likely than women to think about sex and fantasize about having sex with multiple partners. In fact, a multi-billion dollar industry - pornography - exploits this basic sexual difference.

Given this basic biological difference, here are some key differences between men and women when it comes to cheating:
Men are more likely than women to cheat with someone who is less attractive than their current partner. Women cheat up while men are more opportunistic when it comes to cheating.

Men are more likely than women to have a one-night stand. Women are more prone to having emotional affairs.

Men are less likely to consider leaving their partners after cheating. When women cheat, it tends to be more emotionally involved so they are more likely to consider ending their current relationship.

Men are more likely than women to repeatedly cheat on a spouse or partner.