Nel, People in depression tend to isolate themselves from others because they feel blah. It takes a lot of effort for them to do things or want to be around other people because they feel like they need to put on the happy mask. They have no interest in the things that they use to do and they would much rather be alone, sit in a dark room on lay on a couch at times.Depression for men can be very different than it is for women.
As for the anger, yep, it's another symptom of MLC and it takes time for that symptom to burn itself out. They are like two year olds having temper tantrums. If he's being nice, he's hoping that you'll play along w/whatever he suggests or wants. If you go against what he thinks you should be doing, the anger will come out to play. Don't play into his hands. Generally when they are nice, they want something or they've done something that will affect you or your bank account in a negative way.
Keep the focus on you, your financials and treat the situation as a business deal w/the partner trying to back out of a contract for now.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.