Hint- It's not the obvious one.

Here is the question:
What is the number one reason men give for cheating on their partner?

a) Primarily sexual dissatisfaction
b) Other/ no dissatisfaction
c) Equal emotional and sexual dissatisfaction
d) Primarily emotional dissatisfaction

The answers

a) Primarily sexual dissatisfaction - 8%
b) Other/ no dissatisfaction - 12%
c) Equal emotional and sexual dissatisfaction - 32%
d) Primarily emotional dissatisfaction - 48%

This statistic comes from M. Gary Neuman's book "The Truth about Cheating: Why Men Stray and What you can do About it."

According to Neuman, when men don't feel sufficiently valued or validated by their partners for the contributions to the relationship, they are more likely to stray.

Here are some other tidbits from the book.

According to Numen only 12% said the mistress was more beautiful than the wife or partner.

Numan says according to his research, "the number one way the other woman differed from the cheating man's wife was that she made him feel wanted, loved and appreciated - 28%."