Should I expect he will leave me?

He sounds confused. Have you thought that maybe he met someone else?? Maybe that's why he's having second thoughts? At this point anything can happen. I think you should talk to him even if he "gets more depressed".. tell him that you can't sit around and wait until he decides he wants to talk. he can't string you along if in fact he is planning to let you go, you have a life as well. he needs to talk about what's bothering him because otherwise he will make you miserable too. It hurts i'm sure. When I lived with my bf (also of 4 years :( ) and saw my family fall apart I wanted to die. I wish my bf would have talked to me more about it so hopefully your bf can actually open up... good luck