First time I knew my former boyfriend had a drinking problem was when he showed up drunk at my parents' house for a date with me (My mother, who was more in love with him than I was, claimed not to notice he was wreaking of booze). Really felt wonderful knowing he had to get drunk first just to take me out. I wanted to send him home, but Mom said, don't make a scene. So I went out with him. We were driving along, and suddenly, he steered the car deliberately toward the curb and drove on to the sidewalk. He thought it was funny, but I got out of the car, headed toward a bus stop to catch a bus home, and left him there. That was the end of that relationship.
My mother cried over our breakup more than I did. She kept telling me what a good catch he was. Eventually, he married someone else. Years later he was killed in a car crash. DUI. Left a widow and 2 young sons with a pile of debt and no life insurance or savings.
Dodged a bullet there.