My heart goes out to you as you face this incredible struggle, not just in relation to your partner but also in relation to the mental health challenges you are now facing yourself.
No doubt, some of the folk in our life can lead us to feel depressed. When they lead us to ask questions such as 'What's wrong with me, why can't I fix this?' or 'Why aren't I worth the effort?', it can really start to bring us down, while we can also be struggling with a sense of loneliness.
This self-isolation business offers even greater challenge when home base is 'the place where I drink most'. Myself, I'm not much of a drinker but my husband is and has upped the intake since being temporarily put off. His excuse: 'It's my time off', 'til he goes back to work. People will typically tend to excuse their behaviour when they find what they believe to be a valid excuse for it. Alcohol slows the metabolism and messes with our chemistry in many ways. Cue the lethargy and general disinterest in life.
Wondering if there are a number of mini goals to be achieved around your place: Painting, general household stuff, major projects that have been on the back burner that would make a difference in the way of visual reference/sense of achievement? Is there anything in the way of music that generally peps you and your partner up? Is there anything new you've both considered in the past? I know it's a little out there but this could also include intimacy based playfulness and experimentation.
It's tough when you're somewhat adventurous in life or like looking for ways to feel excited in the way of living and you're partner's not in the same zone. While routine offers us much in the way of stability, adding new ventures (adventuring) is a natural part of our evolution. Replacing old ways with new ones is what helps take us far from who we used to be (aka the person who knows only sufferance and little joy).
You're fortunate your partner wants to change (through counseling). This is a good start. Knowing he does not want sameness is hopeful. I recall my years in depression some time ago and found one of the greatest struggles to be not knowing how to change, especially while dealing with the challenging chemistry of depression. Have you asked him what he wants to change or how he wants to change? This could help in managing. Don't take 'I don't know' for an answer.
You're a sensational person doing and incredible job within a monumental challenge. Have no doubt!