1. There isn’t a decrease in non-monogamy. Rather, there is an increase in serial monogamy (which really isn’t monogamy). Think about how many people you’ve dated in your lifetime! People used to get married and stay married, but that hardly ever happens anymore.

2. In a survey of human societies, only 127/840 were socially monogamous (Daly and Wilson, 1983, Sex, Evolution, and Behavior.)

3. It conflates sexual monogamy with social monogamy. For instance, birds practice social monogamy (some for life; other only for 1 or a few years) However, they do practice extra-pair copulation (i.e. cheating).

4. If monogamy was so stable, why is it actually so unstable?

This becomes another game. What is the risk of getting caught? What will happen if I do get caught? What will I get from doing this? All this goes into how you play the game.

For both males and females, infidelity can actually confer a huge benefit that is often worth the cost… especially if you don’t get caught!