So yes, it’s perfectly reasonable to ask how much he drinks.
Not necessarily, and this is why people who don't live with problem drinking in their lives simply don't get it.
For a start, alcoholism is progressive. Nobody goes from a moderate drinker to an alcoholic in one day.
My husband started off drinking 3 or 4 times a week. But those 3 or 4 times would be times I'd bring the kids out for the day. Instead of coming with us he'd get dropped to the pub. He might be only there for 2 hours or so, but it was EVERYTIME I brought the kids out.
So technically he wasn't drinking much but it was still a problem because I was effectively a single parent. To the point of he ever did come along on the very odd day the kids would ask was he not going to the pub.
Drinking interfered with our family life. It was definitely causing me a problem. It wasn't a problem for him however because he said he didn't drink THAT much, and he didn't drink everyday. It wasn't the volume of what he drank. It wasn't even how often he drank. It was when he drank. And when he saw his opportunity to go to the pub.
But I'm sure had I said anything I'd be a nagging controlling wife according to some here?
Then, as alcoholism tends to do, it progressed. It crept up. The volume crept it. The frequency crept up. He went from being a moderately heavy drinker, to a heavy drinker, to a very heavy drinker, to an alcoholic (in my view. He still doesn't think he's an alcoholic because he doesn't drink every day).
People who don't live with a problem drinker tend to not understand. People who live with a problem drinker tend not to ask "how much does he drink" because people who live with a problem drinker know it's not as simple as that.