This is misleading. It was a study of college students who admitted to engaging sexually or romantically with multiple people WHILE DATING.

Many people consider it not to be cheating when you're casually dating, if you're seeing multiple people.

Now if it was a committed relationship that's totally different. But that's not what the study shows. And you can't extrapolate from kids engaged in hookup culture to MARRIAGE and say "78% of married men will cheat".