Most Helpful Girl
This is wrong on so many levels. Let me tell you why. First off, you are betraying your current girlfriend. She thinks that she is in a happy, loving relationship, and yet you are willing to dump her for some girl who you find 'prettier'. How do you think that is going to make your current girlfriend feel, Oh wait, you don't care about her. Why do you think that she isn't good enough for you? Maybe it's the other way around, because your attitude towards your relationship with her is very telling. Your attitude towards relationships is highly unappealing, and I don't think ANY girl deserves that. It shouldn't matter her appearance, or level of attractiveness, you should love her because of who she is not what she looks like.
It is cheating because you are just using your current girlfriend as a placeholder until little miss 'upgrade' comes along. You are the reason many women hate men. Using and taking advantage of their trust and then making them feel like crap in the process, smooth move. I'm sure you will win over your newest crush when she finds out the reason you left your ex. I hope she runs for the hills, for her own good!