I really like this theory. Believe is, after all, a very powerful force, in fairy tales and in the real world.
I’m not sure it would be enough though, for just her to believe that is. It would obviously be a big step but somehow I feel like the believe of one person isn’t enough to break a curse that powerful. Maybe if she got more people to believe? I don’t know, but it would definitely be an interesting curse breaker if that would be it ^^