I said no because I struggle with a lot of mental health issues on my own and have put myself through too much dating drinkers. I think it's a question of how much risk you are willing to take and in this case the risk and stakes can be high especially if you plan to live together/have children together etc.
Part of it is that I have difficulty leaving someone if they relapse and let it end up dragging me down so that's part of my recovery that I need to work on.