Hmm - sounds like he's maybe depressed. Does he just 'go to meetings' or is he actually working the 12-steps with a sponsor. The steps can make such a difference (I know - I made the mistake of just going to meetings and expecting to soak up everyone's wisdom and get better. That worked to keep me sober, but not to help me recover).
The think is, up til now he's had alcohol to boost his esteem (turn him from a geeky duck into a eagle) and now he has to learn to function without that. Maybe his esteem isn't up to initiating a sex marathon. However, he should be learning to take more notice of his responsibilities, not less.