I think that both Charles and Diana were very silly people. Charles was forced into a 'suitable' marriage which he didn't want, and Diana was old enough to know what was going on.
She was not the first, nor will she be the last to have a broken marriage, but she had no money worries, and had so many people dancing attendance on her. I don't see her as innocent at all - just a tremendous drama queen. She was very manipulative, self-pitying, and very fond of other women's husbands.
Charles just seems to be a bit of a nincompoop, and possibly not a good prospect as King. Anyway, we've had Ethelred the Unready, Richard the Lionheart, and now we may be faced with Charles the Gormless.
Camilla? Well, she might not have Diana's beauty, but she seems to be a pleasant enough old trout. I don't see her as being particularly blameworthy - she was part of a triangle of leisured wealth in which adultery and intrigue seemed to be the norm
It's not that important anyway. At the end of the day they are just people like anyone else, and face the same pitfalls and temptations as we all do. They just do it with more funds!