I have had codependent tendencies since I was a little kid.
I had/was working on them when I met my exAH. Signs were there of his drinking problems but I did not actually really see that until after we were married.
I believe that I got into a relationship with him in part to help me look and examine those pieces of my childhood that I was really unwilling to look at. That was not a conscious decision , but necessary for healing for me.
I believe that in part we were attracted to each other because of the codependency/addiction connection. With that said however I believe very strongly in the Three Cs, and I know that my behavior did not cause his drinking, just like my codependency (in my case only) was not caused by his drinking.
Al-anon, therapy and being here all helped. As did reading about addiction.