(LONDON) — The relationship between once-close brothers Princes William and Harry supposedly began to sour when Harry started dating his now-wife, Duchess Meghan, according to a new book, Finding Freedom, which claims to shed light on what caused Harry and Meghan to step back as working members of the royal family.

William, who at that point had only met Meghan, a former American actress, a handful of times, reportedly told Harry, “Don’t feel you need to rush this … take as much time as you need to get to know this girl,” while the pair were dating, according to the book.

William’s reported comment is said by the book’s authors, Omid Scobie and Carolyn Durand, to have had a chilling effect between the brothers, the only children of Prince Charles and the late Princess Diana.

The book also goes into detail about Meghan’s apparent struggles to settle into her new family.

The mom of 1-year-old Archie, her son with Harry, entered into Britain’s royal family as a biracial American woman who was also a divorcee. She gave up her career and life in the U.S. and Canada to live in the U.K. with Prince Harry when they wed in 2018.

“For Meghan, already an accomplished biracial American actress, she faced her own difficulties not just with members of the royal family but with the institution themselves,” said Scobie, also an ABC News contributor.

The book also places some of the blame for Meghan’s difficulties entering the royal family on her sister-in-law, Duchess Kate, whom the book alleges “did little to bridge the divide.”

The authors claim relations between Kate and Meghan and William and Harry were so strained that Kate allegedly snubbed Meghan at her and Harry’s final engagement as working members of the royal family.

“While Harry and Meghan both greeted William and Kate with smiles, the Cambridges showed little response,” the authors of Finding Freedom wrote about this year’s Commonwealth Day service in March at Westminster Abbey.

Friends of William and Kate however are striking back at claims that Kate did not welcome Meghan into the family. Sources close to the couple told the Daily Mail on Sunday that the Cambridges had “rolled out the red carpet” for Meghan.

“It’s really sad because they grew up together, side-by-side supporting each other through the most difficult of times,” ABC News royal contributor Victoria Murphy said of the divide between William and Harry, who supported each other through the death of their mom more than 20 years ago.

Buckingham Palace is not commenting on Finding Freedom, which goes on sale in August. The headline-making excerpts from the book were published over the weekend in the Times of London.

The Sussexes appear to be trying to distance themselves from the book, of which there has been speculation about how closely they were involved.

A spokesperson for the couple told ABC News in a statement, “The Duke and Duchess of Sussex were not interviewed and did not contribute to Finding Freedom. This book is based on the authors’ own experiences as members of the royal press corps and their own independent reporting.”

Harry and Meghan stepped down in April from their roles as senior members of Britain’s royal family. They no longer take public funding and have their own communications team after closing their Buckingham Palace office.

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