Some people are just irredeemably selfish. Some people can't keep their word, don't know what a promise is and don't have the integrity to keep a Vow.
Everybody can be attracted to someone else. Everybody. But not everybody acts on it.
Mostly those of low character and no morals.
If a relationship is wrong and you find yourself seriously attracted to someone else, end your current relationship, with some dignity, first then pursue your other relationship.
Simple.
There's also the part about; why can't people find someone that's unattached? Find your own Man. Find your own woman, don't be trying to steal someone else's. I mean, WTF is wrong with you?
Is it just convenience that you're porking your girl/guy from work?? If that's all it is, then they deserve each other.
I'm married now for a long time. A real long time and I've felt the sexual tensions at work, among friends, acquiantances, etc but I've never acted on them. I don't cheat. Not that I don't look. Not that I don't appreciate the beauty of other women. I do. I for damned sure do.
I just don't act on it. Partly because I respect the other person in my relationship but mainly because --
I respect myself. I don't want to be the cause of all the pain. I've seen it and it's ugly. So much pain.