Hey, Ugh, yeah. I had a friend like this. It used to piss me off like crazy, and I thought she was making a huge deal out of nothing and being immature. This might be what your friend is doing. It certainly sounds like it. However, you need to think about your friendship with her. Do you want to remain friends? You're just going to have to keep in mind that when it comes to this one particular friend, you can't cancel on her. You might want to go about this by not making plans a while in advance, in case something else comes out. And when you do make plans with her, they're final. It's very insulting if you cancel to do something you think you'd like better. Usually people like this are very insecure, and feel rejected when you cancel. I know how annoying it is -- trust me on this one (lol) -- but you really do just need to know how to behave when it comes to this one friend, in order to avoid trouble. It's not worth making a huge deal about.
Keren