What she did is neither OK not normal.

My answer might change if she had come to him acknowledging a terrible mistake and begging his forgiveness. But the fact that she is defending her decision and, presumably, continuing to hang out with friends who are the kind of people who also condone this? No way.

Whether he wants to stay or leave is up to him. Personally, I’d be out the door and I wouldn’t look back. And I wouldn’t be ashamed of it, either. Anybody who asked would hear the same answer, too. “Whoa, you left after just 6 months? What happened?” “It turns out my ex thought it was OK to have sex with a stripper.” That ought to pretty much explain it.