Yes, in the end there will always be many what ifs. I think that Diana made the best out of bad circumstances, and rose above how unhappy her private life often was, by becoming what she was in public. But, that wasn't enough for her, so she sought love in all the wrong places, and it can only be hoped that if she had lived, if she would have found the right person- the last man she was with before her death was almost certainly not that. She thought she had found her fairytale at 19, and so did the world, but that turned sour so she spent the time after that seeking the real fairytale, perhaps, with man who couldn't have given her that. You can't blame her even if she did hurt some people, and I agree, I don't think that was her real nature, as is evidenced by how she was before she married Prince Charles.
As for Prince Charles and Camilla, maybe it is kind of the same thing. I can't really cast blame, and think it was totally selfish. They couldn't marry when they were young, and perhaps were confused about what they really wanted, so Camilla married elsewhere, and Prince Charles had to marry elsewhere. I think if he hadn't had to, he wouldn't have, but he did and it has to be said it it turned out more badly than it could have. But, when someone can't marry who they really want to when they are young, and maybe don't even if they want to marry that person, although they might be attached to them, it really can't be said to be surprising that some years later when they marry for the sake of convenience, their heart isn't in it. That is just very human, and so is Diana, Princess of Wales seeking after her marriage went sour solace with other men, when she saw what her fairytale marriage had become. In my opinion, both Charles and Diana had expectations going into the marriage that couldn't be met by it. The most positive things to come out of the whole thing was their two sons, and also the fact that Princess Diana became the figure she was, and that in the end Prince Charles and Camilla finally did marry, and in my opinion, that seems to be, as someone else said something that has worked out well. Maybe nobody really was the loser in the end, if looked at that way. Maybe that is overlooking other things though...