Prince Harry and Prince William's Relationship Is Beyond Repair: 'There's No Going Back' (Exclusive)

Prince Harry laid bare the painful rift between himself and his family in the pages of his memoir Spare last January — and the world learned the extent of the division between Harry, 39, and his brother Prince William, 41. 

But nearly a year after Spare’s publication, “absolutely nothing has changed,” author Omid Scobie, whose new book Endgame is out Nov. 28, tells PEOPLE in this week’s cover story.

In fact, the hurt and anger between the two brothers — one, the Prince of Wales and future King and the other, the Duke of Sussex and Californian — has now hardened into something colder and more immovable, says Scobie: indifference. 

“I saw Harry’s release of Spare as his last attempt at telling his family how he’s felt for years,” says Scobie, who chronicles both the breakdown of the royal family and the weakening of the modern monarchy in Endgame. “Because clearly there’s never been an open enough forum to have these conversations or share these feelings.”

The royal family, of course, is not known for its focus on feelings. But in Endgame Scobie writes that perhaps more than at any other point in history, the family is ignoring its internal fractures at its own peril, because “part of the buy-in from the [British] public is that the royal family is the nation’s family.” And yet, Scobie says, heir-to-the-throne William has prioritized his loyalty to the monarchy, even quietly cooperating with the U.K. press to undermine Harry. (Kensington Palace had no comment when reached by PEOPLE about the allegations.)

In writing Endgame, “I was talking to a source quite early on in the process, and they called Harry a ‘defector’ and said that was William’s view,” says Scobie. “These were two men who once upon a time were firmly aligned in their outlook. One of them had to move on to also protect the crown.”

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But will there be a crown left to protect decades from now? “There’s a real chance here to learn and adapt to modern society and also make up for mistakes of the past,” says Scobie. “It’s their move.” 

Even if the monarchy endures, the question remains of whether sacrificing brotherly bonds was worth it. “These are probably sad realizations that will be had far too late in the journey,” says Scobie. “In the eyes of some within the institution, Harry is a threat to the crown. His freedom to exert his own thinking outside of the confines of the institution has made him the enemy.” 

Which is why for the brothers, he says, “there’s no going back.”