That couple could be good friends of mine, the marriage was on the verge of collapse, he went of with a woman from work, 8 months later he went back home and they get on better now than they ever did before. Don't get me wrong, it took her a long time to get the trust back but she acknowledged that the breakdown wasn't 50/50, she was to blame much more.
It's not for everyone but if there's something to salvage it might be worth the risk.