Weakness. Belle hates that word; she hates the times when it feels as if she's surrounded by it, she hates feeling it herself, and she certainly hates the fact that she is apparently her true love's weakness. That isn't how true love is supposed to work, but apparently it is, and she hates that too. She tells Rumplestiltskin as much one day in the middle of trying to plan for the problem that is Cora… and that's when he tells her something miraculous.
Regina's wrong. She – Belle, the bookworm princess turned caretaker and librarian – isn't Rumplestiltskin's weakness; she's his strength!