Raped at 13, married at 19 and divorced at 21. It's not complicated. She was young and preyed upon.
It seems irrational; but that's youth. And one can only imagine her guidance wasn't so excellent given her Father was her rapist and her Mother seemed to not care.
One thing we see in this family is the obsession with "the perfect image." Everyone. All said, it's explained.
I don't know if the story is true. But if it is, I only hope someone reaches the Queen to tell her that 'substance' is more important than 'appearance.'