OP your posts are all over the place! Did this girl break up with her BF in the last 36 hours because she had a BF in the first post but didn't have one when someone said that you had nothing to worry about when your BF and this girl are in relationships. Maybe because a single girl seems more suspect and we would all decide that in fact your BF was an ass after all??
He is clearly there for convenience.
One thing I learnt very quickly in my current relationship is to ignore everyone else's relationship expectations. If you trust your partner and you love each other then everyone else's opinion doesn't matter. According to my friends, I was dooming my relationship by going on holiday by myself and they wouldn't put up with that. But my relationship was fine. We trusted each other.
If you don't have that kind of trust/faith in each other (and I'd only been dating my partner a few months at that point) then what is the point? You either have some attachment issues to sort out or the trust can't be there because someone isn't trustworthy. Either way, no prime relationship material
What should I do?