Have you ever read a book where the author just expressed exactly how you feel? I started reading a book called Joy School, by Elizabeth Berg. At one point, the main character, a 13-year-old girl, says "And anyway, even when I like a person there is a weariness that comes. I can be with someone and everything is fine and then all of a sudden it can wash over me like a sickness, that I need the quiet of my own self. I need to unload my head and look at what I've got in there so far. See it. Think what it means. I always need to come back to being alone for awhile."
I read that and recognized it, recognized myself. That is it, exactly. I love the phrase "the quiet of my own self". And this is why I read books. To put into words those feelings and bits of myself that I can't express.