premising that I hope it's something else, because the idea that Jill would want to talk about a past sexual experience with Bella when MC is out the door strikes me as colossal nonsense.
It would be too "innocent" an incident to lead to such a reaction
if something like this happens between 2 girls, friends, they have a laugh and it goes away, what would be so terrible that we would never have to talk about it again?
DPC's plans for Bella are hardly predictable, anything is possible from the asylum, to maximum security prison. the scenario of a one-night stand threesome and that's it, I see it as possible only in the scenario where Bella decides to step aside and decides to say goodbye to MC and Jill this way (for whose happiness she has already said she is willing to step aside)