Closing the Metaphoric Door
She ensures that she doesn't let anyone get too close to her. It is a defensive mechanism that she has had since an early age. Even back then, she knew that people are not all that they seem.
They have layers, many layers, and not all of them are good. Some people are bad right down to the core while some give the illusion of good, when really they are not. Alternatively, some people may seem bad when actually they have a heart of gold. You can never know until there comes a time where they must show their true motives.
She likes Castle and thinks he's a good guy. So far he has done nothing to persuade her otherwise. And yet, she can't quite open up to him like he wants her to. She can't offer up her heart and her spirit and let him see all of her for who she really is.
She closes the metaphoric door on him, like she has done so many times before with other men. All the while, she hates herself for doing it, hates that she can't open up to him and she keeps him out of her private life where she can help it. She tries not to let him see just how he affects her.
He pulls at her, like a magnet pulling at its opposite. She tries hard to turn her back and repel him. Survival instincts, she likes to think of it. She knows it is crap. It's pure crap. It isn't survival that she's knocking him back for, but her own fear. She's allowing her fear to consume her – and him alongside her.
She's not helping either of them by trying to push him away and keep him out but she can't help it. Even so, she knows that like a magnet, it is only a matter of time before she snaps and loses her grip and they collide. It's a joining that she is both terrified and desperate for.