One person two personalities

This is about a girl named Alison. She is a vampire with a rosary to seal away her powers. She has pink hair when she is in her human form, but when she is in her vampire form she has silvery white hair with blood red eyes. Her human self is nice and weaker than most people. Her vampire form is rude but quite strong. She runs into a guy named Keith, he is nice and quite shy. When he finds out Alison's a vampire he freaks out and runs away from her, but later regrets it. Eventually he learns to except that Alison's a vampire, but what will happen to Keith? Is he making a mistake?