Good question! My last relapse was caused by being ambivalent about really stopping. I still wanted to believe some of the lies, rationalizations, and assumptions that my AV was feeding me: that an abstinent life would be unlivable and more painful than the drinking life, that cravings would kill me unless I gratified them, that drinking wasn't a problem right now so I could keep drinking right now without problems.
Once I realized that those weren't truths, but were lies, rationalizations, and faulty assumptions that I told myself for the sole purpose of keeping my drinking behavior going, then quitting became much easier. I could have avoided relapse if I'd challenged these untruths earlier.