Yes...I think you know the reality of this not a good sign otherwise you wouldn't have posted in the first place...

Hope for the best prepare for the best and have a candid conversation with him about how his hanging out with his friend who is a girl...if he doesn't understand why you would have a problem with it...you just learned something about the value he places on the relationship he has with you and with her...

Candid assertive conversation doesn't equal aggressively attacking him about this...