There are layers of psychology here. Diana might, at some level, have resented William for everything he represented: The first son of the man she didn't want to marry;
Except that Diana
did want to marry Charles. The marriage rapidly turned out to be a huge disappointment (which was to be expected, frankly; even had Charles not been longing for Camilla, they were an oddly mismatched pair), but she went into it willingly.
I doubt she resented William, but in a way she may have felt that he was not fully hers. As the future King, his father, grandmother (and, I would venture, great-grandmother) had claims on him, and distinct ideas about how he was to be raised that, at times, no doubt overrode Diana's wishes.
I'm sure Harry, as the spare, got some of that, but I doubt it was ever to the degree William did. They grew up under the overwhelming fact that William would one day be King, and Harry would not. That's pretty crazy, when you really think about it, and seriously, who could fault Harry for sometimes thinking that unfair?
So William was Charles's, while Harry was Diana's, and she may have tried (consciously or not) to make up to Harry for the fact that he was "the spare" by indulging him more. By then, her marriage was in the shitter and Charles was openly sleeping around (including with the boys' nanny), so I can see her identifying more closely with Harry, the superfluous prince who would always live in his brother's shadow, who in turn identified more with her.
Cut to 1997, and Diana suddenly dies, and not only is Harry a young boy who has lost his mother, but also his staunchest and most uncritical ally in a system where he's always going to be the extra, the spare.
Narcissists typically stop developing emotionally at about age 14 or 15. Prod them a bit, and that bratty teenager comes to the surface. I think Harry stopped at age 12. Diana died, and that was it. Because even for a Narcissist he comes off as childishly incapable of the kinds of insights I'd expect to see in someone just a couple of years older.
She obviously doted on Harry and no doubt fed her own feelings of resentment and inferiority into him.
Yeah, I'm sure there was a lot of, "Papa and Granny and the newspapers have made Mummy sad, but I can make her feel better." He was her little white knight; her Good King Harry. But he couldn't prevent her dying.
Then Meghan comes along and exploits it to the hilt, no doubt spinning the story that she can complain to HR and cry racism until the problematic incumbents are shuffled out of the way, putting Harry on the line to the throne. She knows enough of the history of the royals to make Harry think it's possible. It doesn't matter if she knows it won't actually work, she's doing it to secure Harry's loyalty and affection.
I'm now convinced that Harry's exploiting Meghan, too. I used to think it was, "poor dumb, emotionally-damaged Harry, seduced by a vile temptress," but that ITV interview—man. That's changed everything.
I think, on some level, he saw her as the exact kind of woman to marry in order to get payback against his family. Her inappropriate behavior, dress, and grooming; her inability to be properly deferential to senior royals or follow protocol; that she was an American actress from a family full of fuckups; her brashness and lack of shame in demanding what she wanted; and yes, even her mixed race all made her the antithesis of what the RF would want in a new member, and, I suspect stoked his attraction to her.
But while Meghan is the bad girl, there to embarrass his family and fuck their shit up, her outsider status, and the ways in which she was challenged by the RF to straighten up her act, take him right back to Mummy. And that's obvious in the way he keeps saying Meghan is so much like his mother, when anybody who remembers watching Diana back in the day can tell you that, other than proclivities for drama and attention-seeking, they are nothing alike.
I've said it before, and I'll say it again: he should have stayed in the Army. It gave him structure and purpose and kept his wilder tendencies from coming to the fore, and he obviously loved that he was treated like one of the lads. He could have made a decent officer, given time. Not a distinguished one, but the sort that keeps out of the way and gives all the orders his sergeant wants to hear.
I absolutely agree with this; I thought so even before he married Meghan.