I was married for five years, only to find out my partner cheated on me. Yes the relationship had been crappy the last year. But I kept my vows and she didn't. All I asked was that if and when one of us felt the relationship was over, and/or that we were interested in someone else, then that person needs to tell the other first! It hurts so bad, and so deeply erodes my trust and faith in people, that I pray that you either work on your marriage or let it go. Please, this is how it starts, with "innocent" flirting. Just be honest for both your sakes.