It really is hard when we see someone slip because there are so many aspects:
1. You feel that person's pain and wish you could help but are powerless
2. You wonder if you could have done anything to have prevented it.
3. You hope and pray that they make it back because they've become a large part of your life and you need them
4. You feel like "there but for the grace of God, go I" and wonder if/when your urge will be so strong you can't resist
Our friend is obviously wanting to come back, he continues to post. Hopefully eventually he'll be back.
In the meantime, for anyone who hasn't slipped, keep posting here, keep working whatever program it is that works for you. And keep being here for your friends. I know I need you.