I will use my family for an example so we can see where it may happen more often. I know very few of my buddies that have ever done it once married, but remember, most have my friends have been married for less than 5 years.
My grandparents had 4 daughters, live in iowa, etc... My mother and father made it 11 years, aunt and her first husband lasted 15 years, and other 2 aunts are still married. My youngest aunt has only been married for 6 years and nothing yet. Of the other 3, 2 husbands cheated and 1 wife cheated.
So 75% of marriages someone cheats.
66% of the cheaters are men, 33% women.
This is what I know to be true.