I know I'm not the addressee, since I'm not a man; however, I'd like to give my input. I think the answer is not the one you want. It just depends on the guy.
I know that I would expect my last boyfriend's reaction to be upset. I mean...we've shared a girl before, but if I made out with a girl at a part, he would probably be upset when he found out. Especially if he found out from someone else. Not only that, but he would probably get upset that I would do that at a party, in front of other people. If I'm at a party without my man and I'm making out with women...that might make others believe that the relationship is not good.