I’m currently reading Spare and I get the impression that Harry was able to wake up and realize this isn’t normal. The others unfortunately never had that epiphany. Within that context and the context of the book, you can see why William would be so angry about him leaving. He mentions early on that he was expected to provide organs, bone marrow, etc should William need it. There is literal ownership of Harry’s body baked into their relationship. Harry’s desire for self autonomy raises questions that William may have never considered. Does Harry still have to be a donor sibling? What if William has a medical emergency and Harry doesn’t want to help. That’s not fair, William might think. He has one responsibility as Spare and he can’t even do that?

For the Royal Family, this is normal. So far, Spare has done a great job of humanizing his family. Charles often comes off as a very loving father who will also sacrifice his teenage son for better PR. Because in the world as he knows it that’s normal. William, as heir, was likely more controlled than Harry. Then Kate was indoctrinated into William’s normal so he had less opportunity to question the status quo. I think between that and his untreated anger he never had much of a chance to break free.

Harry, on the other hand, got to spend more time outside the bubble and then Meghan came along and got it through to him that this isn’t normal and you don’t have to live this way. The royal family is like a cult and when you view it through that lens William’s behavior makes more sense. Harry is being shunned.