Welcome. ANything I say is pure speculation of course but it could be that he is just being honest and needs to concentrate on his recovery. A valid thing for him to do. It could be he is headed for a relapse. Either way, nothing you say or do will change what he does.
There is nothing you can do really other than accept that at least for the time being a realtionship with him involves this sort of thing. You get to decide if this is the sort of relationship you want. Acceptance of what really is, what he need and wants, what you need and want, is the only way forward.