Many people have an egocentric view and feel their bosses are concerned with every minute detail of their careers. Nothing could be further from the truth. It might have nothing to do with you. Just because the boss has been in a bad mood or has been ignoring you this week does not mean that he is plotting your demise. Your boss could have had a fight with his spouse or could have been in an accident on the way to work.
Bosses are human and are entitled to be in a bad mood.
You aren't always the cause. Don't read too much into things. If you want the straight scoop, just ask your boss directly. Your job is to make the boss look good and to shield him from surprises. Head problems off at the pass.