Listen to DontRemember. Don't bother going to marriage counseling with an active addict. Therapy does not work unless the addict is in recovery first. You get into the room with them, you pour your heart out, meanwhile they are sitting there finding new ways to manipulate you because you've shown them your soft underbelly. Eventually the counselor gets manipulated into helping the addict gaslight you... because their manipulation makes YOU seem nuts.
People want reasons for crazy behavior: maybe he was stressed, maybe his life got worse... maybe, maybe, maybe. It doesn't matter what the reason was, there is no reason except "that's what addiction is like, it's progressive." The problem with trying to find reasons for the behavior is that it allows the addict to externalize blame... and allows YOU to do that too. So you think: if only I make his life less stressful by doing xyz, he will drink less. No. It doesn't work that way. Nothing you do can stop him if he doesn't want to stop.
What you can do, is get help for you. Learn about codependency. Keep reading SR and posting here.