I disagree about the 'need' thing - some people drink a glass of wine in the evening, but it doesn't mean that they have a problem. Many marijuana smokers do so for the same reason and at the same 'dose' as an evening drink. It's not necessarily indicative of an addiction.

However, I agree with everyone else regarding him drawing the line and making you choose between living with it and losing him. He's making his choice as to which is more important. The other thing, and only you would be able to assess this, is that I strongly object to using ANY substance - wine, beer, marijuana, liquor - as a way of self-medicating. But again, you would have to determine that because we don't know him.