Like one of the messages says don't worry about it too much, but also remember that if he wants a break then it is his loss.
I do beleive that men behave strangly at times and it could be because something had triggered it. Don't ask him about it, if if wants you he will come to you then ask him. If he doesn't have a good explanation then forget him. Its only a year of your life! U need someone stable. I have recently broke up with someone after five years who became abusive and unstable let it go!