What is fair?

Okay I need to know what is fair here, I always feel like im the bad guy. Basically I started seeing a girl and shes making things move way to fast for me and I dont think im interested anymore. WE have only been out several times but she is obssessed with me and thinks this is going to last forever. Not only does that scare me but I much rather get to know her more before makign this serious. So I guess my question is, is it fair for a guy to date a girl for a little and realize its not working, were just not getting along and ditch or should I have realized that before we went out? How mad would she be if i bailed?

if you feel like things are going fast and you rather slow it down a bit, have a talk with her and explanined to her how you feel. I'm sure she'll understand.