Stefan, I think you might have missed the mark a bit in your discussion with Ashley and Michael. When Ashley described what went on after her mother died mirrored exactly what my siblings and I went through with our Dad after our mother died - although there was a 3 year span between mum's death and dad remarrying.
I am one of 5 and our family was very close and I would say we all had good relationships with both our dad and mum. Mum died of cancer after a 2 year illness. Dad was grief stricken. He spent 2 to 3 years in misery. Then he started seeking out a new relationship. The woman "he chose" was totally unlike mum - immodest, not smart, and very, very possessive. Soon after we met her we saw her darker side - Dad was oblivious to this. One of my brothers, one of my sisters and I all had children at this stage. Dad doted on his grand children. Immediately his new fiance drove a wedge into our relationships, claiming to Dad that we were all unwelcoming and not accepting of her. The two siblings without children were, by contrast, in her eyes, wonderful (although we know they held the same views of this new woman as the other 3).
For Dad's sake we initially reserved judgment, but when they got engaged my brothers tried to reason with Dad - not to not re-marry - but to get some councelling and work out some of the differences. Heedless of the suggestions they got married. We spent the next 19 years with very little contact with Dad. After any contact we had with Dad there would be accusations of some misdemeanour or another. Our children grew up barely knowing their grandfather. Dad died about 4 years ago, and in the weeks after his death his widow has gyped us out of what Dad had put in his will, she made sure we were not allowed to be involved in the funeral.
Many people have commented to us that they would never have imagined Dad would have taken this course. He so loved his children and his grand children, but for the "love of a woman" he was prepared to go along with her manipulation lies and deceit.
As I listened to you talking with Ashley I thought "Stefan just doesn't get it". This new woman in the Dad's life has turned his affections. It happens and it is quite inexplicable how or why a father could do this.