I think it's up to each of us to learn to manage our own emotions. You are probably better off leaving your boyfriend alone to sort things out especially if what is upsetting him has nothing to do with you.
A mature person doesn't take his or her anger out on someone that has nothing to do with what is causing them to be upset. They know what makes them feel better, (a type of music,an activity/hobby, a movie, certain foods, a good work out at the gym, sex, or something as simple as sleep.
"Anger is the mask that Hurt wears"
Most anger stems from feeling taken advantage of or feeling mistreated in some way.