I think that Brooke Davis said it better than anybody when she said some times people put up walls, not to keep people away. But to see who cares enough to tear those walls down.
Has anybody else ever done that? Pushed someone away? Even though they're the very best person to have ever come into your life, even after the way they make you feel. You know, a part of you is just scared. And it pushes, and pushes and pushes, because you're so haunted by all those previous dickheads that abused your trust when they said they'd never go that you don't really believe anybody who says it anymore.
And then they want to know whats wrong. They want you to explain. To put into words how you're feeling. To tell them that you push because you expect that one day, they will go. Just like everyone else before. And you push because the quicker that happens, the less it'll hurt.