Best Girl Friend Likes Me But Has A BF Complicating Situation?

[LonelyWolf]

I've been best friends with this girl for a while me and her talk on the phone alot and everything and talk in school and sometimes i see her around places we say hi to each other and hug and everything. The problem is me and her both likes each other,but she has a bf however she told me she is gonna break up with him but she is saying its hard for her to do because she doesn't want to hurt her bf's feelings. Also,she hasn't been talking to him for 2 straight weeks cause she told me he is being an asshole to her,she even told me he was on a boat with 4 girls and he smokes weed with another chic and goes to parties. But,she still has feelings for her old ex bf from the past which who moved to a different state so she told me she can't be with him at all but she still likes him.And she likes this other dude a little bit not as much as me she told me she likes me more.Now my question is wtf is going on why does she still have feelings for her old ex bf who moved and why can't she break up with her bf she has now and just simply go out with me? exp and advice please