It usually takes more than three days to get the alcohol out of your system, so my bet would be on the phenomenon of craving, something that is activated once alcohol is in the body.
It has been described as a craving so powerful it is beyond the menatl ability of the sufferer to control it. I know it is powerful, I have lost jobs directly as a result of being unable to stop and return to work, once I had taken the fatal first drink.
To get over that hump the best option may be a short term, like a week or so, of hospitalisation, hopefully in a detox ward that AA members call on. After that, an intensive effort at the AA way of life. Those two things together can be a pretty effective recipe for sobriety.