She doesn't really want to be with you, and when she finds another guy she will ditch you, until then she will string you along, but when you don't meet every demand she wants, she will just have a fling. It also sounds like you already kind of know this, but are too scared to be alone.
I think it may be time to try to talk it out with her, and if she still refuses, then dump her. Relationships have to be a two way street. If they are not, then the relationship cannot be. Learn to accept it. I know that is a hard thing to do, when you feel emotionally attached to someone, but sometimes it is the best thing to step away from something and really try to look at it from a objective perspective.