In my case I now know (took 20 years to work out/filter down) due to my W's family of origin and her subsequent life events that she has always since I have known her been a High Functioning (borderline) Borderline Personality. She has expressed her anger through acting out in passive aggressive ways and by withholding affection/love.
The affair she had 4 years ago and what looked like MLC was probably triggered by me accepting the situation deciding to have a happy life anyway and stopping enabling the PA withholding behaviours. Plus a spilling over of the 'toxic emotion pail/locker/draw' that she had split away: end result BPD crisis: looking for external source of happiness - affair - objectification of OP - triangulation - projection - deception self and otherwise etc.
I think that those that have a difficult mid-life transition are those that have there pre-existing personality traits or disorders. A well adjusted individual would not behave in these ways no matter what.
Just my thoughts and opinions.
The roots of the disorder or the disorder start in childhood long before you came on the scene. The BPD was there since teenage years at least.
