Why so selfish ?

Okay. So I have this friend. A lot of friends, I guess.
So this friend knows almost every boy from one of the other schools in the campus we go to.
Out of 50 boys, she like about 10. Out of that 10, there's 5 she wants to be "emotionally" attached to. But here's the problem ( during the time):
Boy #1 likes me. I like Boy #1. We go together
Boy #2 likes our friend. She likes Boy #2. They go together.
Boy #3 is talking to a friend of hers. They may get together
Boy #4 && Boy #5 are dating other girls.

She doesn't want to talk to Boy #6-10, because she's depressed. So... I mean... what do you want us to do ? Break up with them or have them break up with their girlfriends so you can be satisfied? There are handful of boys that like her && try to talk to her, but she's not having it.

Truth of the matter is, she's boy crazy ! A teenage, boy-crazy girl doesn't want to be completely, 100% emotionally attached. However, how can you be emotionally attached with 5 boys ? "Emotionally attached" means she wants to pick a guy, settle down && live her life with said guy. So you're just going to pick one out the group like he's an apple in water ? It doesn't work that way... She has the hardest problems with guys...

...Why so selfish ? Why do people hate to see someone happy for their own pleasure ?