Well he’s obviously addicted. You can use once a month and still be addicted. Alcohol and coke come hand in hand, the minute u have a few drinks your phoning a dealer.
If he never wants coke again he is going to have to quit alcohol as well. Or else it’s just gonna be a vicious circle. He needs to delete all dealers nums and friends who use. Or get a new number. Avoid pubs and mates. And start changing his life around. And maybe join cocaine anonymous and work the steps and go to a meeting. There could be underlying issues from his childhood why he uses, but doesn’t have to be the case.
When the coke wears off it sends you suicidal and depressed for days. It’s an awful drug. And ruins family’s. I’d make sure you see him putting the effort in. Or start thinking of your self.