M/J solo is basically pretty much a given with how Josy is in 11, i don't really see them coming back from that. I mean, can it happen, sure. But I don't expect it.
Nerds, yeah, we'll see how that one's gonna turn out. I mean they do have a lot of Blackmail Material and apparently also remote access to the DIK's Laptop (not sure if still available, I would have formatted the whole damn thing to be sure, but it seemed that Rusty just "cleaned" it up).
Bella, that is indeed a big Question mark. What I think that Room is, is a Nursery and she may have lost a Baby (or couldn't have any) and that is why her Husband left. Or, for the kinky ones here, it is/was her Husbands Sex Dungeon for her but she didn't want to go that far and then he left. (lol)
Stephen, that could also go many ways, tbh. I kinda see him quitting Uni and leave, the "talk" with Quinn (when Bella was walking past, Quinn looked really really pissed), was already quite a while after Mona left. And he could have just told her that "it" is over and she's not getting any more Money from him. I would count that as a possibility, especially with the Divorce. (read more like mid life crisis).