Mary P Jones has written two excellent posts over at A Room of Mama's Own in which she gives her answer this question. The first focuses on what addiction is and what it isn't. The second is more about the actual answer to this question. Good stuff.
Personally, I like to think that I would take my commitments, both to the person and to the institution of marriage itself, seriously enough that I would stay married, even if she turned out to be a full-blown addict of any sort. This is largely due to my upbringing and the very strong emphasis in my religious denomination on the sanctity and permanence of marriage. Nonetheless, they are called vows, and I also want to take any vows I make to be taken seriously. Primarily by myself, but also by others.
Staying married, however, doesn't mean living with or putting up with the crap. Frankly I'm amazed that Bitter Cookie stayed with me for almost 24 years. Things went downhill almost continuously during throughout our time together. There was a brief, inexplicable rekindling of our romance for a few months less than a year before she filed for divorce (I'd been sober 3 years at the time), but other than that, the relationship just continued to worsen. It was so bad, that one of my daughters actually told me she was glad we got divorced. In the end, Bitter Cookie decided that she liked me even less sober than drunk and that was it.
Notice I started off saying, "I like to think..." The fact of the matter is that I've never really had to deal with the kind of behavior like that the spouse of an addict like the Junky's Wife describes in her blog. I look at my life today, at the rudeness and inconsiderateness that I put up with at home and how I react to it, and I see that it probably wouldn't be that simple for me. My friends think I'm nuts to stick around but for whatever reason, I seem to lack "courage to change the things I can." Well, that, in part, is what working the 12 Steps on this relationship is going to be about, I guess. Sigh!