Hey what's up, first post here. So I was at a party with my cousin and her co-workers. I don't know anyone there but the party was a surprise birthday thing for a mutual friend of theirs. Maybe 30 people at the most. Every attractive guy there had brought their girlfriend except for me, and the birthday girl who I was interested in kept making eyes at me. I knew she was interested based on her body language and I was pretty stoked. Fast forward, this guy shows up who I assume is a mutual friend of theirs. The girl I was into starts hanging around him constantly. Taking selfies with him and being in his team in beer pong. I don't really know what happened. Obviously this guy had history with her, and I think that was the only difference. I think we're pretty equal in the attractiveness department but he seemed to be more in control of this particular social group because they were all friends. Help me break down this interaction please