How do i deal with my boyfriends bipolar disorder?

My boyfriend has been diagnosed with bipolar disorder.the doctor says its sesonal but its driving me insane.i don't know what to do to help. it's so hard for me because i have never been through this situation.he gets extremly moody and i don't know what to do to help! its like im riding a roller coaster! at times he's happy and im happy but when he gets mad i get frustraded help give me advice on what i should do.How do i deal with my boyfriends bipolar disorder?
my husband is bipolar and i am not sure what you mean about seasonal because i have never heard that... bipolar is a chemical imbalance in the brain. his oldest son is bipolar and taking medication to control it, but both my husband and our youngest son control it without medication. you have to be calm and research the subject so you can be more understanding to what is happening. we have been through 4 bad times with the bipolar and i have found the best thing i can do is leave him alone until he calms down. talk to his doctor but i would try to control it without medication if possible... you cant help just be understanding