It's really impossible to know...I mean, it all comes down to chemistry - moods are chemistry, reactions to moods are chemistry, drugs and alcohol are chemistry etc...from your description it could be so many things. When I was on my own zoloft 'high' I married someone I barely knew. This looks like obvious 'manic' behavior, but at the same time, I believe falling in love (or lust at least) can mimic and/or induce manic-like behavior - so did I get married because I was in love or manic? or was I 'manic' because I was so excited to be in love or because of zoloft? or was it some 'perfect storm' of love/lust, zoloft, and brain chemistry? Who knows.

It sounds like whatever the reason, your gf is in some serious distress and is attempting to self-medicate whatever pains her. The wrong medication (and you don't have to be bipolar to react badly to zoloft) and alcohol will only worsen whatever it is...I hope she can get help soon.