I think the fiance is in denial when he claims that she would not drink and drive....a recovering alcoholic can be the best person in the world, but once they "pick up that first drink" everything changes....
they can and will do things that "they" would not do in their normal, rational "sane" sober mind.....as they say in AA, the first drink is too many and 1000 isn't enough
In "AA" they do the "12 steps">> at some point they are told to repair the "wreckage of the past" with the help of a sponsor...this can involve making "amends"...ie going to people from past that you have wronged, or hurt, or screwed over when you were drinking, etc
it sounds to me like the visit to the stepfather /maybe the ex were part of this...however, ONCE SHE PICKED UP THE FIRST DRINK LAST WEEK SHE SHOULD HAVE NEVER GONE THROUGH WITH THE AMENDS/VISITING THE PAST>...one drink and you are back to "step one"....you have to start all over and just go to meetings (or rehab) and get sober all over again
I wish I knew how long she had been sober?? I personally think that pressures, fiancee "illness", pushing for marriage, maybe trying to do the amends/visit the past were too much for her
Once she began drinking nothing she did would be rational...once an alcoholic starts drinking there is NO telling how bad they can get, what dangerous or foolish things they might do, what a mess they can and will make
I am not afflicted myself, but I have had relatives and "sig other/s" who were...
as for the fiancee....some of those who continue to love an alcoholic also need to work the steps in Al-ANON and get out of denial....it sounds to me as if he was not JMO
Added : not to mention that she also had some depression issues/meds going on...and a family history of suicide (her mother)