What I would try to do in your situation is to understand his behavior in terms of coping strategies and maintaining the harmonious flow of the relationship.
If I’m mad at someone, it does neither of us any good to talk about it. I know full well that my anger does not really stem from that other person, it’s coming from me.
This happened a lot in the early days of my relationship. I simply was not a nice person to be around when I was angry. It took me a long time when I was in my twenties to learn how to control it. But in the context of a relationship, my normal defenses can fail because I’m not as in control as I am normally.
An effective, but not ideal intervention was to simply not talk to her until I’ve calmed down. Many times, when I got angry at her, I was able to bring it under control and apologize, but many times I couldn’t and so I’d drive her home, angry, and call her up in a few days after I’d analyzed what went wrong, worked out a strategy for avoiding that trigger in the future, and the event itself was ancient history.
Anger is one of those emotions that it’s not safe to have anymore. It’s easy to do things when you are angry that before would be waved off, but now looks really scary and is often grounds for ending a relationship over.
I have been told that I’m really scary when I’m angry. Your boyfriend might not have that. But at the same time, it really changes the context of an interaction when you’re mad. Guys who are really cerebral don’t really have any defenses against anger and so when it happens, they often feel really helpless. I know I do.
I’d guess that his avoidance behavior is stemming from that. He feels different when he’s angry than you feel when you’re angry. I’d suggest trying to understand it and maybe work out a better protocol that fits your needs better.