Updated

For Andrew Morton, there’s no doubt in his mind that Prince William contributed to Prince Harry and Meghan Markle’s exit from the royal family.

In 2018, Princess Diana’s biographer wrote a book on the Duchess of Sussex titled "Meghan: A Hollywood Princess," which explored the former "Suits" star’s rise to stardom and whirlwind marriage to Harry, 37. On Tuesday, the British author re-released his book, titling it "Meghan and the Unmasking of the Monarchy."

Featuring new chapters and interviews with some of Markle’s family members and closest friends, it examines the Duke and Duchess of Sussex’s lives behind palace doors as well as what ultimately led to their decision to step back as senior royals.

Andrew Morton book

Andrew Morton's updated book on the Duchess of Sussex is titled "Meghan and the Unmasking of the Monarchy: A Hollywood Princess." (Grand Central Publishing)

"I was surprised by the parallel between Diana and Meghan, especially in those first two months inside the royal family," Morton told Fox News. "Meghan said she felt low and isolated – Diana felt the same. For Diana, she felt [the palace] was a place of cold energy – a far cry from what felt on the outside. It was astonishing to me."

PRINCE WILLIAM’S ‘BOLD AMBITION’ WITH EARTHSHOT PRIZE AWARDS HAS MADE PRINCE CHARLES 'VERY PROUD OF MY SON'

Markle, a former American actress, became the Duchess of Sussex when she married Harry in 2018 at Windsor Castle. The couple welcomed a son named Archie Harrison Mountbatten-Windsor in 2019.

While the romance seemed like a fairy tale made for Hollywood, the couple’s departures from royal duties began in 2020 over what they described as the British media’s intrusions and racist attitudes toward the duchess, 40.

British royal family

From left: Meghan, Duchess of Sussex, Prince Harry, Duke of Sussex, Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge. (Photo by Max Mumby/Indigo/Getty Images)

Morton claimed that William, who is second in line to the British throne, contributed to their decision to step back.

"He obviously had an influence in it," Morton alleged. "I think that Harry resented the fact that he supported his relationship with Kate Middleton over the years. We forget that the palace didn’t believe she and William would marry. They didn’t think she had what it took to be the future queen, initially. But Harry always supported her. He was always friendly with Catherine. They were always joking and laughing together. And the fact that William couldn’t do the same for him did not sit well with Harry. There’s no doubt that there was a divide between the brothers."

CLICK HERE TO SIGN UP FOR THE ENTERTAINMENT NEWSLETTER

Morton alleged that William, 39, didn’t instantly welcome his sister-in-law with open arms because he was wary of Markle’s Hollywood background and how it would impact the palace.

Prince William

Prince William is second in line to the British throne. (Getty)

"William is a cautious guy," he explained. "He spent eight years with Kate and they broke up briefly at one point before they married. For Harry, it was instant when it came to Meghan. But William felt it was just too quick. And he didn’t know much about her family. I remember in those early years, anything that was being reported about Meghan’s family was coming from her brother and sister speaking out to the press."

The Duke and Duchess of Sussex eventually moved to the coastal city of Montecito, California. But in the wake of quitting royal duties, they gave an explosive TV interview to Oprah Winfrey, in which the couple described painful comments about how dark Archie’s skin might be. The duchess talked about the intense isolation she felt inside the royal family that led her to contemplate suicide.

William was the first member of the royal family to speak out about the accusation, telling reporters "we are very much not a racist family."

CLICK HERE TO GET THE FOX NEWS APP

Prince Harry Meghan Markle Oprah Winfrey interview

This image provided by Harpo Productions shows Prince Harry, from left, and Meghan, The Duchess of Sussex, in conversation with Oprah Winfrey. (AP)

In that same interview, Markle cleared the air about an ongoing rumor that she allegedly made Middleton, 39, cry ahead of her royal wedding to Harry. Markle said it simply "didn’t happen" and instead, it was the Duchess of Cambridge who made her shed tears.

"In leading up to Meghan’s wedding, Kate was experiencing a tough pregnancy [with Prince Louis] and didn’t have much energy to bond with her," Morton claimed. "Even after the wedding, they were still getting to know each other. But Meghan was really angry with the press office for not defending her when the tabloids began pitting them against each other. A press officer told her they cannot deny or confirm every single story that’s being written about the royal family. It would never end."

"I’ve spoken to people who know Kate, I’ve seen her in action and she’s not a confrontational person," Morton continued. "She’s someone who wants to get on with things. Both women did not want to fall into the trap of being seen as dueling duchesses by the press. They were cordial to each other and friendly in public. But Meghan did not feel supported."

Meghan Markle NYC

According to Andrew Morton, palace insiders alleged they tried to help Meghan Markle before the Duchess of Sussex headed back to California with her family. (Photo by NDZ/Star Max/GC Images/Getty Images)

Still, Morton claimed palace insiders insisted to him that they tried to help Markle early on as tabloid stories intensified.

PRINCE WILLIAM THINKS PRINCE ANDREW IS ‘A RISK’ AND ‘A THREAT TO THE FAMILY’ AMID SEX ASSAULT LAWSUIT: PAL

"It’s obvious Meghan was entering a new world," said Morton. "But it’s my understanding that they tried to help. Diana spoke about the men in gray who were hostile to her because they were supporters of Prince Charles. And they had problems pretty early on in their marriage. But Meghan and Harry were a double act. There wasn’t a cigarette paper between them. They were talented together. And Meghan was seen out and about. Friends of mine used to ring me up and say, ‘I just saw Meghan at such and such.’ She did have a life outside of palace walls and in those early days, she was very popular."

On July 1, which would have been Diana’s 60th birthday, William and Harry put aside their differences to unveil a statue of their mother in the Sunken Garden at London’s Kensington Palace. Royal watchers had hoped the ceremony would provide some insight into their strained relationship.

Prince William Prince Harry statue unveiling Princess Diana

Prince William and Prince Harry at Princess Diana's statue unveiling. (Getty Images)

But the brothers are on different paths. William has pressed on with royal life and the never-ending demands that accompany his role as second in line to the throne. As for Harry, he and his family have no regrets about moving to the U.S. in search of a more peaceful existence that he could better control.

"Harry has an idyllic life in California," said Morton. "There isn’t an executive in Hollywood that would say no to the Duke and Duchess of Sussex… It’s quite the transformation for them."

The Associated Press contributed to this report.