Is My Friend Bi-Polar?

I don't think she's bipolar, normal teenage emotions running through her head. The symptoms you've described are responsible as a result of her boyfriend and their disagreements. Bipolar is spontaneous, you get what we call rapid cycling, it's hypomania, a mild state of euphoria and hyperactivity. You get mania, which is more intense enthusiasm, and thirdly you get the depressive state which corresponds to depression. That's why it used to be called manic-depression (mania plus depression), but now Bipolar is the common term. I think that unless your friend can get more concrete diagnosable symptoms except for anger and depression, it's not really a cause for concern.