Your story is pretty much what I went through with my RABF. Everything going great then he told me almost verbatim what you heard: he loved my support but can't be in a relationship. You seem to be taking it much better than I did.
In hindsight I think they start to obsess over the new relationship much like they obsessed over alcohol and that isn't good for their recovery. In other words they replace one thing for another. Not saying his feeling aren't sincere, they were probably deepening and warning bells went off in his head. If he hasn't entered into a relationship sober, this is all new territory for him.
Kindeyes's advice is right on the money. Recovery is selfish and it should be because they are relearning a life coping without booze. Something you or I take for granted. If things don't go well, we don't drink to excess. We cope. Relationships are stressful, even GOOD stress is hard for the newly recovered to handle.
All I can tell you is what I did when I was in your spot. I backed off, he knew I was there but I pulled back really for my own benefit because I was falling for him fast. I read up all I could about alcoholism and recovery, talked to people who had gone through it and once I realized it wasn't personal or 'rejection', I was able to be supportive.
Sadly, he relapsed and now I see why he wasn't able to be in a relationship, they are so much more fragile than you think. It took a lot of energy for him to appear like he was coping when he was just getting through the day, resisting drinking. Communication is also key. I almost didnt believe him when he told me about going too fast etc so when he relapsed I felt horrible. I know it wasn't my fault but all the things he was warning me about were true, not a way to reject me.
Long story short, his relapse brought us closer, he is in a long term recovery program and I miss him seeing him relapse was very very hard so listen to what he is telling you. Be that supportive friend and good things can happen
