The Duke of Sussex and the Duke of Cambridge did not speak for two months after the Sandringham summit sparked by the Megxit crisis, a royal writer has said.
Omid Scobie – co-author of Finding Freedom, which chronicles Harry and Meghan's life as royals – said the Sussexes' decision to reveal their plans to quit without warning the Windsors caused the most upset with William, and the rift between the brothers will take some time to heal.
Harry and Meghan released their bombshell statement about wanting to step down as senior royals in January, prompting the Queen to call a meeting at Sandringham with the duke, his older brother and their father, the Prince of Wales, to deal with the crisis.
The couple's final public royal engagement was the Commonwealth Day service at Westminster Abbey in March, where Kate was accused in the book of barely acknowledging her sister-in-law.
Scobie, speaking on True Royalty TV's The Royal Beat, said: "Where it really went wrong for Harry and Meghan and the Cambridges was that decision to go public with the roadmap to their new working model, the statements that weren't discussed internally.
"That's really what caused the most amount of hurt to William because he wears two hats.
"He's not just the brother. He's also a future king and he felt that that damaged the reputation of the family, that it put family business out in the public domain when it should have been discussed privately.
"And there was a lot of hurt there that continues to this day."
He added: "It's why we saw such an awkward moment at that Commonwealth service.
"The brothers had not spoken since around the time of the Sandringham summit. They hadn't seen each other. And, you know, that's really going to take some time to heal."
Scobie also suggested that Harry, who has outlined his personal commitment to tackling institutional racism, will at some point address his own past mistakes.
He was widely condemned in 2009 after being caught on film calling a former Army colleague a "Paki", and in 2005 he caused outrage when he donned a Nazi soldier's uniform complete with swastika for a fancy dress party.
The author said: "He's on a journey at the moment and I do think that at some point we'll hear him really talk about that journey and what he's learnt on that.
"But I think at the moment ... he's still educating himself. Maybe he feels he's not there yet."
He described Harry and Meghan's new £11 million home in Santa Barbara, California, as "pretty much their forever home".
Kensington Palace declined to comment.