It's a standard break-up excuse, and used to brush someone off or break up a relationship without giving a real reason.
She (sounds like something a woman would say) could just be trying to let you down easily, meaning she most likely doesn't hate you (a good thing).
At WORST she finds you very annoying, and at BEST she's in love with you but feels too guilty, has low self worth, or any other of numerous possible hang-ups.
But I could be wrong.
If I am, see >>2