If it’s true KP was cheerfully allowing the press to print anything they liked about Meghan with assurances she wouldn’t complain or sue even when the lines were blatantly crossed (see printing her letter to her father), maybe he blames William for not stopping it happening?
I think Harry and William have had a very toxic, one sided relationship for a very long time with it being made clear to both of them from a young age that William was the one who mattered and Harry was just there to back him up. I don’t think any brotherly relationship would do well in those circumstances.
It only worked when Harry and William both agreed with that point of view. With Harry deciding he didn’t want to be an attachment to his brother for the rest of his life (reasonably), but William seeing this decision as a betrayal, their relationship was only going to go downhill.
Jason Knauf agreeing to give evidence against Meghan in her legal case was unprecedented as far as I can tell. I can’t imagine he would have done so without at least tacit permission from William.
I feel sorry for both of them (and Kate and Meghan). I know they have massive privilege but they also have a horrendous level of press intrusion in their lives.
Basically, I think both William and Harry feel betrayed by their brother and I’m fairly sure that both would only agree to reconcile with an abject apology from the other. Since neither think they’ve done anything wrong, I can’t see that happening. It’s sad and an indictment of the Royal system.