Yes, the feeling I get is that it's maybe something they did back then and it turned into habit and it must be weird now when they're supposed to have grown out of it. Because of Kate and because they surely can get separate rooms, money-wise, and because maybe that seems a bit codependent, but in the end it's part of the ritual and part of the performance and part of their relationship (and I don't say this as to invalidate their actual relationship, but the fact that their tension bleeds out of their concerts so much just leads me to believe their performance and their private life are actually very closely connected). It must be strange being used to sharing a room and then not doing it anymore because Jamie has Kate now (and I think it's probably strange for both Jamie and Alison, even if in different ways). I mean, I would get lonely if I was Alison. (Oh, and now I'm sort of desperate for fic where Alison gets lonely and so she gets into the habit of taking groupies back to her room when Jamie has his own room with Kate.)

Totally possible that something did happen with a groupie and that's part of the awkwardness of it. I mean, dealing with groupies is a bit awkward for other band members even if they're just friends (I've seen it happen), so it was probably very awkward for Jamie and Alison. I imagine them at the beginning, starting to get people interested in them because it was all so intense, and then one night Jamie asks Alison if he can take a girl back to the room and she says yes because it's not like she has any right to say no, but she really didn't want him to, and then it's tense between them for a while.

Why can't I stop imagining tense and awkward scenarios between them? God.