Hey 😊
I'm so sorry, what a difficult position to be in. I have some experience of this. So I'm not necessarily best placed to give advice, but I didn't want you to be or feel alone.
The reason you're posting this is because you know the answer... of course it is too much!
My grandad (alcoholic and non functioning the last few years) has over a box a day (about the same as your partner last night), and whilst it would floor the most of us, he can hold a conversation and stumble around. Alcohol tolerance doesn't mean it's okay to drink more.
It is totally normal for an alcoholic to trivialise their behaviour too.
My grandad who, until recently, was never aggressive and functioned his whole life (including his high pressure job as a structural engineer), clearly had an issue which we all used to just think "he likes a drink"... But eventually spiralled and became horrific to watch. It's really tricky and sensitive to broach, but a difficult conversation well worth having.
You know in your heart you have no control of his decisions, and he has to decide for him. That doesn't mean you can't raise it and say how uncomfortable you feel and how worried you are. I had a small version of this with my partner and I got through to my partner by saying, how would you feel if I drank this much? And he was mortified. But it's only a few weeks since this, so I'm no expert!!
Would he be open to a challenge like "dry January"? But say, dry October or something? He feels fine getting up after a skin full, he will be fantastic not drinking at all. You could do it together?
Other than that you can either tell him how you feel, and see if anything changes. If it doesn't, ultimately the decision lay with you as to if you live with someone who gets blind drunk every night (no fun for you), or if you accept it's not a life for you and leave.
Fingers crossed a chat will get the ball rolling for recovery from this!