H..How does that work? Does it mean he and his wife are no longer like Married Couple and more like two people sharing the same family with the same house and same bill?
Does he still have actual intimacy with his wife or just pretending in public? Does his relationship with the S-I-L means more than just sex?
Also what about night? after sex and he wants to sleep? did he stay with the sister and went back to his wife's room afterwards?
That sounds so vague.