The choice for him to move in so soon was made so that the three of us could have a better place to live in and because when we made the decision he was at the apex of making all the positive changes in his life. D and R were getting along really well as friends and D had been living in a single and really wanted roommates and people to live with because he felt like living by himself was causing some of his problems.
Our new place is much nicer, and R and I could not financially support it on our own. We also are all on the lease, so he has as much right to the place as we do. I don't feel like we could financially or legally ask him to move out. There really isn't anywhere for him to go.