King Charles III is said to be "devastated" by his strained relationship with his youngest son Prince Harry.

Vanity Fair’s royal correspondent Katie Nicholl recently wrote a book titled "The New Royals: Queen Elizabeth's Legacy and the Future of the Crown." In it, she explores what the future holds for the House of Windsor following the queen's passing.

Harry and his wife, Meghan Markle, announced they were stepping back as senior members of the royal family in 2020. In 2021, the Duke and Duchess of Sussex gave an explosive interview to Oprah Winfrey in which Harry claimed his father stopped taking his phone calls and that he had been cut off financially. That same year, Harry discussed his mental health struggles and why he left the royal family in the Apple TV+ series "The Me You Can’t See."

Britain's King Charles III and Britain's Prince Harry

In "The New Royals," Katie Nicholl claimed that King Charles III is heartbroken over his strained relationship with his son Prince Harry. (Loic Venance/AFP via Getty Images)

"Charles absolutely has been devastated by what has happened," Nicholl told Fox News Digital. "If you think back just a couple of years around the time of [the Duke and Duchess of Sussex’s] wedding, the relationship between Harry and his father was, I think, probably better than it ever had been… Harry and Meghan spent time with Charles and Camilla in Scotland. They went on holiday together. It all looked very rosy and very happy."

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"I think Charles has been devastated by how things have spiraled," Nicholl shared. "And he is hopeful that there will be a reconciliation. I think we saw that in the very… public olive branches that were extended to Harry and Meghan. After the queen’s death, particularly in that first speech that Charles gave to the nation, he spoke of his love for Harry and Meghan. He addressed them on first-name terms. He made the concession to allow Harry to wear his uniform when he was standing vigil by the queen’s coffin… And of course, there’s the matter of titles, whether [his grandchildren] Archie and Lilibet will get [them]. Will that be… the final olive branch that is offered? I think we’ll hear about that imminently."

The queen passed away on Sept. 8 at Scotland’s Balmoral Castle. She was 96. Charles, 73, immediately became king. In his first speech as monarch, he spoke of his "love for Harry and Meghan." When Charles was officially sworn in by the Accession Council on Sept. 10, he used an ink pot that was reportedly a joint gift from his two sons. Then on Sept. 13, Charles, and the Duke and Duchess of Sussex, were spotted at Buckingham Palace together as they waited for the queen’s coffin to arrive from Scotland. Then for the queen’s funeral service on Sept. 19, Harry was seen walking behind his father as they appeared to show a united front.

King Charles Prince Harry reconciliation

Katie Nicholl claimed King Charles III is still "hopeful" for a reconciliation with Prince Harry. (Matt Dunham - WPA Pool/Getty Images)

It's believed the Duke and Duchess of Sussex headed promptly back to their home in California after the funeral service. However, sources told Nicholl that Charles remains hopeful that he and Harry, 38, can mend their differences.

"He does want to sort his relationship with his son," said Nicholl. "He wants to do it on a personal level because he loves his son. He’s never stopped loving his son. He may not be happy about everything that’s been said, but he wants to have a relationship with Harry and he wants to have a relationship with his grandchildren."

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Nicholl also claimed that before Markle spoke out about the struggles she endured as a royal, Harry’s stepmother Camilla attempted to offer a helping hand.

Camilla, Duchess of Cornwall and Meghan, Duchess of Sussex

Katie Nicholl claimed that Queen Consort Camilla "made herself available" to newcomer Meghan Markle. (Chris Jackson/Chris Jackson/Getty Images)

"I think Camilla’s role as a peacemaker has not really been well known until now," she explained. "It’s my understanding that Camilla’s a very family-oriented woman. She never wanted to step on any toes or get too involved in other family relationships. [But] she did make herself available to Meghan. There was that common thread here in that Camilla was very much an outsider, far more than Meghan was in marrying into the royal family. So she was very well-placed to give Meghan some advice and offer some counsel. But for whatever reason, I don’t think the Duchess of Sussex took it."

Nicholl alleged that when she asked her sources about what Harry’s relationship is like with the queen consort, she was "met with silence."

"I was able to shed quite a lot of light on [Prince] William’s relationship with Camilla, which is very cordial – a very good relationship," said Nicholl. "But in recent years… When you think back to Charles and Camilla’s wedding [in 2005], Harry was the first to offer his congratulations and how he was thrilled to have Camilla marry into the family. And yet, he’s been very silent about Camilla recently. There was no word from LA when Camilla was given the Order of the Garter, which is the most senior award that the queen could have ever given her. Similarly, there was no word from the duke when the queen made it clear it was her sincere wish for Camilla to be queen consort. Harry stayed very quiet on the subject of Camilla. And of course, that’s fueled a lot of speculation that he’s going to be writing about that relationship in his forthcoming autobiography."

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Queen Consort Prince Harry

Sources told Katie Nicholl they wondered if Prince Harry will detail his relationship with Camilla in his upcoming memoir.  (Anwar Hussein/WireImage)

In June 2021, Random House announced that Harry was writing "an intimate and heartfelt memoir."

"I’m writing this not as the prince I was born but as the man I have become," Harry said in a statement at the time. "I’ve worn many hats over the years, both literally and figuratively, and my hope is that in telling my story — the highs and lows, the mistakes, the lessons learned — I can help show that no matter where we come from, we have more in common than we think. I’m deeply grateful for the opportunity to share what I’ve learned over the course of my life so far and excited for people to read a firsthand account of my life that’s accurate and wholly truthful."

The publisher announced that the untitled book was expected to be released in late 2022. However, no new developments have been announced since then.

British royal family

Katie Nicholl said the future of the monarchy now rests in the hands of the Prince and Princess of Wales, along with King Charles and Queen Consort Camilla. (Max Mumby/Indigo/Getty Images)

Nicholl believes Charles’ focus won’t be on Harry’s book, but rather on the future of the monarchy and what it holds for the Windsors. And she hopes her book sheds new light on the royal family.

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"I hope that people will read the book and really feel that they understand the queen," she said. "I hope they have a real understanding of her legacy and why she was so extraordinary. I also hope they come away with a real understanding of Charles. I try to break down some of those myths and misconceptions about him that have continued through news cycles but actually are simply not true. I think I paint him as a very caring and doting father, as a very family-oriented man, which I think is a side that a lot of people don’t get to see of him."

"Ultimately, I think my book is a very optimistic look at the future of the monarchy," she continued. "I don’t cover it with roses. I point out the very clear challenges and the obstacles that lie ahead. But I think the tone is overall positive because Prince Charles comes to the throne as King Charles III with a wealth of experience. The dynasty is secure… We have two generations of heirs… If they can connect with the public, if they can remain relevant and, I suppose, prove that there is a purpose for the monarchy in an ever-changing, ever-moving, modern digital world, then I think the future is a happy one."

The Associated Press contributed to this report.