Help! I need advice on a boyfriend with a bad temper!

I have been with my boyfriend for 3 years, we are in our early 20s. I love him very much and I know that he loves me. I trust him completely and he is one of my best friends. He has many great qualities and treats me well, has a good job, we have good conversations, have fun together, laugh together, helps around the house (we live together), etc.
Unfortunatly he has one major flaw and that is that he has anger issues. He gets set off by small things and ends up being disproportionately angry for long periods of time. He is not violent, does not call me names, and does not usually even yell but he is visibly angry and withdrawn. He has an ability to make a situation very tense in a matter of seconds when the anger switch is on.
I love him but this issue has put a barrier in our relationship and I am wondering what can be done about it. We have talked about a future together but I wonder if this is a deal breaker. Any insight or advice is appreciated.