Maybe I am being overly critical. My original thought process was that it takes two to tango and one partner can not always know how satisfied the other is. It just seemed to me that your argument has it's cake and eats it too. "If there were problems in the relationship - yes" "If I don't think there are problems in the relationship - no" But I can understand that this argument could be a little broad..
Meliai said it best and I agree with her. But to answer this thread without dodging it, as a general rule no I would not put up with it. If I did put up with it, I'd feel sorta whipped as a man. I'm more of a if you fail my standards I'm not afraid to be single kinda guy, and personally this approach has saved me a fair amount of drama and seems to give off vibes of self confidence which helps with the next relationship.
I think it depends on the circumstances, how you feel about your lover, and whether your relationship is worth saving (meaning both have the will to save it). One -- just one -- "mistake," especially early in the relationship or while it's going through hard times... I could forgive that under certain circumstances. If it happened again, I highly doubt it. And as Duck said, prolonged, conscious betrayal ends the relationship then and there.
to comment on what meliai said, the problem with that theory is that if you were having problems in your relationship, and your partner didn't even talk to you about it, and instead went out and cheated on you, you would be really hurt, and pissed off, and it would certainly not help the situation. if my now husband had tried to talk to me about things before he did what he did, things would have turned out totally different. and i agree zorba the grape, if this were to ever happen again, i'd be gone. once, i can forgive, but you do it again after seeing how much it hurt me the first time, you most certainly don't care about me and there is no point in going on together.
Most likely not. We're very in touch with each other as a couple and if we have a problem, we talk it out and become closer for it. If he were unhappy and started having feelings for someone else, he would just tell me so we could break up. He's a wonderful person, and if he wanted out of our relationship he'd never suddenly stop caring enough to hurt me like that. We've both been cheated on before and it just destroyed us. Neither of us would forgive the other if we had an indiscretion so I doubt either of us would do it in the first place.
I have a couple different thoughts. First of all this can't happen again, but for all of you who say "you deserve better" I agree. The question is will you find better? I have seen my parents divorce and re-marry. Their relationships now aren't nearly as good. The fact that they gave up of their relationship because of principals in my opinion is dumb. I know they both would have rather stayed with each other and worked through it. As for a kid (now adult) it is the worst thing. Even now we have to do everything separately. My wife and I have talked in detail about always working through it. Just because someone deserves better doesn't mean they will find it. They could spent the rest of their lives settle with someone and have no history. The fact he has done it a couple times is dumb. but now you know and have confronted him about it, it has to stop. Take time and heal together. Then let it go and focus of your relationship. Make it stronger, better. Do things differently. Don't get divorced because of the principle of it. He fucked up, if you still love him and he loves you, work it out. Grow stronger together. You can reinvent your relationship. Best of luck