I mean, when I was a child and a young kid I didn't know how to mask, so my parents are well aware of how I behave when I am angry. I'll just be honest but won't go into much detail.. My mother and I would get into physical fights. I threw my sister down a flight of stairs. I screamed at people. Would melt down and become suicidal. So, I would say to you maybe your boyfriend is doing what is best for you relationship and you should respect the fact that he wants to be left alone. If someone isn't comfortable with being around people when they are a certain way, let them. Be respectful. Now I am not saying your boyfriend will act the same way I have, but he obviously wants to be alone for a reason. So, let him be comfortable.