What I'm trying to say is if you cheat on a girl knowing that it's wrong and continue doing it even though the girl you are cheating on means the world to you then thats messed up. If she means the world to you and she is faithful to you then you should treat her the way she deserves to be treated. Not tell you you love her then bang any other random girl. Mistakes happen, we're all human, we all get tempted, and some of us fall to that temptation. The difference is do we realize and own up to our mistakes or choose to indulge ourselves in them.
I'm not saying anyone is a coward for cheating once. People make mistakes. I think they're a coward if they continue to do so dragging some poor woman along who is nothing but faithful b/c they are to scared to man up to their issues. Same goes for women.
Just my opinion. If you want to be with a particular person, be faithful to them. If you want to be promiscuous then do so at your own expense.