(revised) What do I do Please tell me?

I wrote my scenario before but I left out a lot of information. I cant stop thinking about this girl who lives in the apartment next door to me. I always thought that she was really hot but she lives with her boyfriend. Then her and a friend knocked on my door and invited me over to a party. The thing is that there were only 2 other guys. Both of them were definitely weird and not good looking at all. I would hate to sound shallow but women are usually attracted to me. I am no Brad Pitt. Realistically, people say I look a lot like Dennis from its always sunny in philadelphia. haha The point is, I don't have any struggle finding girls in NYC. But this girl next door is special. Anyway, we were talking and she had brought up the fact that she broke up with the guy she is living with so I thought that I was in the clear. Then she threw another party tonight and I wasnt invited. I am starting to think that the challenge of this girl is what Im seeking but at the same time, I feel like if she liked me, it would be the best day of my life. I would truly appreciate it. It wouldnt just be some sort of catch-and-release. What the hell do I do??? I hope that I am not mistaking flirting for genuine kindness. I feel like such a talking like this haha.