I don't think Diana was a gold-digger. I think she married him thinking he loved her. I think he married HER just to create good-looking offspring.
I remember reading that she found out somehow that he still loved Camilla and not her, but she went thru with the wedding anyway.
She was no saint, but I put most of the blame on Charles and the rest of the Royals. It was all politics and Diana was just a naive 19-year-old.