Even though alcohol is not his drug of choice, my BF and I go to Al-Anon (for me) and AA meetings that are in the same location at the same time (different rooms). We ride together so I know he's there. Take him to the rooms. Take him to a Dr. to see what will help reduce the cravings and or mitigate his withdrawals (naltrexone, etc). Do NOT give him "permission" to use. Tell him you expect him to be nice and loving toward you even if he isn't using.