Well when I think about it, I think that is the reason. As a general rule 你 dont really come across people in life with such a personality like Rosalie's. I mean who has everything they could ever wish for and still be a total cow at the same time?
I think we all sorta get where Rosalie's coming from wanting to be human, live a normal life, grow old with the person 你 love. Who doesn't want that. That sure sounds like the best wish in the world for a vampire.
Rosalie's also a vampire with un-natural human abilities that we cant have. That's proabley why we 爱情 her to death!!!