He always knew he had a problem with drink, but he externalised the 'whys' - it was never his fault, and there was always an excuse. He drank because something good happened, he drank because something bad happened, he drank because he was doing something productive (as a 'reward'), he drank because he was bored. The truth is he had a very neglectful childhood, he comes from a family of alcoholics and the only real way they bond is through drinking copious amounts of whiskey together. He kind of understands that but doesn't want therapy because he doesn't want to talk or think about it (unless he's really drunk).
I think we're on good terms because of how deeply we know each other and how long we were in love for, and we were actually very good at communicating. His alcoholism was also not severe, although he did have bouts of hiding it so I'll never know the true extent. His main thing was going on random crazy benders where chaotic and destructive things would happen. He was never violent to me or DD thankfully, mostly just very irritating or very occasionally could get paranoid about random stuff and accuse me of doing things I'd never done!
Ultimately the drink came first always, and always will. Even severe, painful gastritis over the last six years hasn't curbed his alcohol addiction, and neither did leaving (his drinking has worsened now he doesn't have to hide it).
From the snippets in your post, it sounds like your partner is a more 'traditional' alcoholic - drinking every day etc.? Does he acknowledge he has a problem? Does he want to change? I say this with a bit of futility as I think it's very, very rare for people to change.