Because in some ways, being in love with someone is a very selfish kind of love. It demands something of them, doesn´t it? It requires some sort of reciprocation, a kind of emotional contract. You tell someone you´re in love with them, and you expect something in return. And if the feeling is not matched, then you have a problem. Because you still have this expectation, this hole to be filled, and you´re convinced that the other person is the only one who can fill it. But they are telling you that they can´t, that they are not even going to try, but you still have this hole inside you, this place you have made to hold another person, and you can´t just make it go away..So you end up hating this person you´re in love with, because you need them in order to be whole, and their saying no feels like they´re ripping out that piece of you. Every time you think of them, it´s like they´re ripping it out over and over and over.