I hate to say it, but I'm not sure if they really can get back to the way they were - does that make any sense? Too much between them now maybe, or too much time since Sam came back and he didn't let Dean know. It's hard to put my thoughts into words for some reason. It may take Dean a while to get over that.

I don't think your expectations were too high - you're not the only person I've heard voice your thoughts :o)