Eh first of all- Bob's an A-HOLE! Second- it is a very tuff situation for you, sorry you're confused. I dont even know what to suggest. I'd personally say something to her if it was a very close friend, b/c I know I'd want someone to tell me if Joe was acting this way. Whether he not having sex w/ these girls or not, if thats even the truth, he's still putting himself in a bad situation. And I'm SURE if she was doing the same thing, he'd flip out. HOWEVER- sometimes telling the girl is not such a good idea...it can back fire and you wind up the a-hole trouble maker and your FI gets blamed too, etc etc etc. It basically depends on the girl and how you think she'd react...sorry, I'm not much help huh?