Parent issues, pet issue, job issue.

He lives with is dad.His parents are separated. His mom lives with someone else. But he gets proper support & attention from his mom dad & also from that new person for a long time.He had lot of girls in his life.He loved someone but their relation didn't work because of his ego anxiety. Then he started taking drugs. Then he went to some psychiatrist and comes out of it. After that he kept a pet. last year he died accidentally. But he blames himself & feels guilty for his death. Then he joined wipro. But he wasn't satisfied with the job and the location as well. Recently he resigned from the job. We are in a relation for 8 months. For some months he becomes angry irritated very easily. When I try to discuss anything about his mistakes he becomes furious he starts to find my mistakes then argues. He used to say I don't understand. Mybe can't move on easily from probs as I can.That's why maybe I don't understand depth of his situation.I want to help him out.I need some permanent solution