There's this guy who I've known for 2 years now. He's a friend of one of my best friends. I see him sometimes when I go out with my friend. The dude is pretty chill, probably around the same SMV as me looks wise. When I see him, it's always fun. He even asked me to hang out 1 on 1 sometime.

But this is the second time he has tried to steal my girl at a party. The first time was 2 years ago. I met a girl at a party, and she invited me to an after-party. This dude tried to steal her from me, but it didn't work. Thought he was a snake back then, but didn't really care, since I barely see him anyway.

Last night he did it again. I met a girl at a party. She was pretty drunk, and we were making out all night, she wouldn't stop kissing me. Even whispered in my ear that she wanted to fuck me at her friend's house. I thought, so far, so good. She says that she's getting drinks, and I told her ok. I was talking to her female friend, who was smoking hot as well.

1 hour goes by, and my girl is nowhere to be seen. I turn around, and she's talking to that snake dude, who saw me making out with her before. He was clearly trying to make a move on her. It's not my job to mate guard, it's the girl's job to turn him down. Anyway, I proceed to party with her female friend, and other girls.

The night goes by, I go home with my friend, and this female friend of the girl is with us. She tried to call the girl 10 times, because she was supposed to sleep over at her place. The girl is nowhere to be seen. We dropped her friend off at home, and this morning she called me, asking if I knew where her friend was, because she had not heard from her all night.

Turns out she went to an after party with the guy, and they probably banged. I don't know why this makes my blood boil so much. I don't care about this girl, but this is the second time this dude has tried to steal a girl from me. I would never fight over a girl, but I don't know why it makes me so mad.

How to deal with this situation?