Interesting. It happens all the time that men cheat on their wives. Then they get divorced and marry the mistress. What happens next - they cheat on the new-wife-former-mistress. Sometimes they are already cheating BEFORE they get married.
So what were the mistresses thinking? That he is really a faithful man but he made an exception for me become I am so irresistible. No. He is a faithless, disloyal, narcissistic, egomaniac. He would cheat on anyone. No exceptions.
The same applies to gossip. Someone shares with you some JUICY gossip about someone you know. This guy has what to sell! Really interesting stuff!! REMEMBER - IF HE IS SPEAKING ABOUT OTHER PEOPLE BEHIND THEIR BACKS, HE IS ALSO GOING TO SPEAK ABOUT YOU!!!
This is a כלל גדול בחיים. It can be applies to many different scenarios.