Statistics on relationships between married men who leave their wives for another woman?

A bit on a negative side. Married men thinks that if they leave their wife for their mistress, his life will be different. He will assume that what he have now with his mistress will be much fun that what his been having with his wife, until he finds out the behavior of his mistress or vice versa. Few married men who left their wife only last 3-4 months, and there are some that last a year, no longer.