I think there is hope, but only when an addict has been working hard at a recovery plan, and continues to. Then i believe there is real hope.
However, we have to remember, that relationships are very difficult to keep on track even without an Addict in our life. Just regular relationships are hard.
So for an Addict who is putting all their energy into staying off drugs, i guess the pressure of a relationship is too much to cope with.
My opinion is keep doing what you're doing. Give him the space he needs until he has real recovery time under his belt, then he might get back in touch when he's ready. If so, great. If he starts using again during this time, then you'll have had some distance there and will be able to keep it.
It's a VERY difficult situation. Good luck. Keep coming here as it's a good support network.