Well that definitely makes me sad. If he ever boinks someone else that will be it for me. That's a one way ticket to divorce in my eyes. Separated or not.
I have a friend who's husband cheated on her when she was pregnant with her first child. She divorced him (he subsequently married the other woman and they just had a baby together) and a few years later she married a great guy and now they have two kids together and are blissfully happy. I know one way or another I'll be blissfully happy again someday too. I hate that I can't see it from where I currently stand.