His father who cheated on his mother and treated her appallingly. Why are people so quick to rewrite history. Charles has no morals is that what you want from your future king?
Oh you sweet summer child, all kings have mistresses, in modern times more usually married women (so they cannot be pressured to break the marriage for them) was ever thus. Edward VII and Mrs Keppel (Camilla's great-grandmother). Charles II and Nell Gwynn (and many, many more). The French kings and their courtesans. It's an accepted part of the role. Hell, even Queen Victoria likely got it on with John Brown, after Albert's death.
Diana knew all about Camilla and the fact Charles was stuck on her before she was married. Everyone in their circles did. Diana was a blue blooded aristocrat from one of the biggest aristocratic families and knew how the aristocracy behaves, which is many of them on both sides of the marriage consider discrete affairs to be fine once heirs are born because they marry for reasons other than infatuation. She chose to marry him anyway. Marrying Charles or rather, the Prince of Wales, was her career choice. She said when she was young she either wanted to be 'a dancer or the Princess of Wales'. She chose to date and marry Charles knowing his reputation and even the fact that Charles had dumped her own older sister, Sarah, for being indiscreet, didn't bother her. She wanted the job rather than the actual man. She pretended to love all the
tit Charles liked, which was short term successful and long term moronic, because it meant two totally incompatible people were now stuck together. Several other rich and aristocratic women Charles was actually infatuated with dumped him because they wouldn't put up with his fascination with Camilla. Diana could have done the same, but she wanted the job. What was also interesting about Diana is that she was actually good friends with Charles's other mistress, the married Australian heiress Kanga Tyron, would hang out with her and wore her fashions at big events. She didn't care about Charles's sexual infidelity, she cared about Charles's connection with Camilla being far greater than with her.
Diana also cheated on Charles with endless men, some of them very much very married men. Diana actually broke protocol and viciously harassed the wives of these men and was a factor in the demise of marriages. Diana shagged her own bodyguard and finally a tacky Arab billionaire
bleep-hopper for the sole purpose of spiting the Pakistani doctor Hasnat Khan who refused to marry her. His mother also regularly called the paps because she enjoyed the chase and because she liked to use them to rub certain activities in various people's faces. She also refused proper royal protection officers who wouldn't have let her get in a car with a drunk driver and would have made her wear her seatbelt. Diana was no saint, and if she'd lived instead of participating in her own destruction I think more people would see it. She spent a lot of time not with her kids but chasing men, any man who'd look at her twice. She also bullied her sons' beloved nanny by imagining she was sleeping with Charles and spreading lies about her having an abortion, publicly, in the nanny's hearing. She was a spiteful and vindictive
witch in many ways in her personal life (as opposed to her public image), with as many or as few morals as Charles, if you wish to frame it that way.
On the other hand, she was kind of a snob and would have dispatched Markle instantly upon meeting her. She thought Sophie Wessex was beneath her because she lacked aristocratic blood, so if she'd been around you can bet she would have put the kibosh on Markle's grabby self as a marriage partner quickly, whatever Harry has deluded himself into thinking.