Very long time lurker, and very rare poster here....but, after watching the videos, I have to say, I'm kind of in the same line of thinking as to the theory you just posted (JoCoKSEyes, at 7:27 p.m.)
I work at my alma mater (Virginia Tech), and I have chosen to keep my drinking going for years since I graduated (living in a college town...)....and while drunk and/or high (especially when I was 18-mid twenti-ish : ) ), I have reacted completely erratically to what I perceived (in whatever altered state) as negative news from and/or about a romantic interest.
Not kidding. Hid under a bush on campus at age 18, sobbing, and wouldn't come out for hours, in spite of what my also-drunk but worried friends said to try to cajole me out. And many other examples that I won't list here....
I hate to say it, but from my experiences in the past (and sadly, even recent past....), altered state reactions to bad news, especially if one has depression or anxiety (which I'm not necessarily saying that Hannah suffers from, and is still young, could still be undiagnosed or not recognized), makes me think that she's had some sort of accident. : (