I have no idea about your friend quit - but if his head is anything like mine would be doing that, I feel for him.
I know my dysfunctional relationship with alcohol is a permanent one - because I figure it's not really about the alcohol so much at all - it's about me.
I had dysfunctional relationships with a lot of other things and substances too.
There's no day in the future where I'll be able to go back to drinking and be 'normal' about it - and I'm at peace with that - in fact I'm happy about it
and...beer and wine nearly killed me - so go figure....
D