There is no right thing. I have noticed there is a point at which I adjust to an environment and it becomes easier - I thought I was going to go crazy the first few weeks I was in a student hostel but it was fine. I would never have adjusted to sharing a room though.

He may feel bad if he comes home and bad if he stays. Could you visit and make the decision on what you see? Or are your tickets in 2 days to go somewhere else?

I do think if he can he should stay but not if he is really unhappy.