Strangely the opposite situation happened in my marriage .... my husband pursued me in college, he was the responsible, hard working, truthful level headed person I wanted for a partner. My dad had been an alcoholic and I was adamant about not exposing myself to that horrible self destructive life as an adult .... and that I knowingly never would have married anyone that showed any signs of alcoholism. I had seen close up how miserable life with an alcoholic was.
However ... I married someone that had all the healthy qualities I needed in my life and he fulfilled those behaviors ... and I had no desire to change him into someone else .... and so it remained for seven years. However, in a matter of weeks, he went from having an occasional beer once or twice a month .... to suddenly having alcohol become the focal point of his life every day and dramatically transformed him forever ...and remained that way until the end of his life. In my case I married a round peg that fit into a round hole ... but years later, that round peg chose to evolve into a square one - and our relationship was forever altered and never fit together again.