Why King Charles Feels 'Betrayed' by Prince Harry and Meghan Markle: Royal Author (Exclusive)

'Spare,' Prince Harry's memoir, is due out Jan. 10.

King Charles III is not looking forward to Prince Harry's forthcoming memoir. In an interview with ET's Rachel Smith, Christopher Andersen, the author of The King, claims the new monarch views his son's memoir, as well as his and wife Meghan Markle's other public statements about the royal family, as a "betrayal."

"This is going to be another series of grenades that they're tossing into the palace. They are terrified... Charles and Camilla and the rest of them, about what Harry could say," Andersen claims. "Particularly because I understand [the memoir] has so much to do with his upbringing, the marriage of Charles and Diana. It's all viewed through this lens now."

While Andersen notes that Harry was "the rebel prince" during his early years, during which time Charles "really came to his rescue," now, with his memoir, Spare, Andersen claims Harry has "gone a step too far in terms of what Charles is willing to put up with."

"We will have to wait and see if they can bridge the gap," Andersen says. "The trouble is Charles has got to take this monarchy in the direction he wants it to go, and for that to happen, I think he's always felt he needs all hands on deck. That would include Meghan and Harry."

"I think to a certain extent Charles feels betrayed by Harry... because, in the beginning, the royal family really embraced Meghan," he continues. "... It was Charles who walked Meghan down the second half of the aisle when her father wouldn’t show up. It was Charles who befriended Doria [Ragland], Meghan’s mother. They really seemed to have clicked. So now to have her say the things she's saying and sort of turn on them in that sense is very hurtful."

Even so, Andersen says that "over the past couple of years, of course [Charles] sent messages to Harry that he's still beloved and that they want him back. He's praised Harry’s work as an environmentalist. He included Harry in his speech that he gave after the death of the queen."

From Harry and Meghan's perspective, though, the couple "felt dissed" by a series of perceived slights at Queen Elizabeth II's funeral, Andersen claims.

"I think Harry and Meghan really felt dissed in essence by the rest of the family, by not being shown the proper respect that they felt they deserved," Andersen says. "They were shoved off to the side. There was no warmth really between or connection between Harry and the rest of the royal family."

"When Harry and Meghan showed up, I think [they were] expecting an olive branch to be extended in a real way [and] it wasn't," he adds. "... At certain points during the funeral of the queen, you could see the hurt on their faces, I think, and the disappointment and the anger. If Charles had hoped to have Harry excise something out of the book that he's writing, I think that [possibility] flew out the window as a result of the way they were treated at the funeral."

Prince Harry's Spare is due out Jan. 10. Christopher Andersen's The King will be released Nov. 8. Tune in to Tuesday's episode of Entertainment Tonight for more of ET's interview with Andersen.