That's a big question to even begin to guess at a distance without more data, JB. Have you done even a "first level" tour through some sites about bipolar to see how much their descriptions fit? (See ads at right for one sampling). Has she been evaluated or treated for any other psych issue? If so, what does her shrink or therapist say? Have you spent time on any message boards or forums where bipolars or their loved ones converse about the daily details of having it or coping?

Those are the places I would begin to start assembling some clues. And even after you test your hypothesis with some research,  it will then take a good shrink to confirm or suggest how to treat. In general, bipolar is severe enough to be treated most of the times with meds along with whatever other self-help makes sense. And meds = psychiatrist.

In all events, best of luck to you!