The last couple of days I was leaning to voluntary disappearance, well not quite voluntary in the sense of purposeful, but rather as a flight reaction to a mental break caused extreme stress.
I'm rethinking that because why would she go to the H&F after the football game. Why not drive off to who knows where immediately after she told her ex "I've gotta go" .
Then again, maybe her anxiety was still building to boiling point until the visit to the apartment building, and whatever happened or frightened her there was the last straw that caused her to be so overwhelmed that she had to flee, whether in a lucid state or not.
As for Seven, I honestly think she would have left him or brought him back to the house, contacted a friend to take care of him (friend who had a key, or leaving the key hidden in some spot outside) had she decided to flee earlier that day. In addition, I'd think she would have contacted her ex to keep BW a few days longer.
IF she did flee from the H&F, I believe it might have been a spontaneous, desperate and sudden decision where nothing mattered other than to escape.
However, if she did flee in her RR a state of psychosis, I would think her driving would have been erratic, causing a police stop or accident and she would have been found. I don't know.
Just thinking aloud. It now seems a bit farfetched, ....but these things do happen (my colleague I spoke about before, Mitrice Richardson, Teleka Patrick, Margot Kidder and her breakdown, etc)
I can't even speculate anymore, ...maybe foul play is involved.