Prince Harry had reportedly started showing signs of a rift with elder brother Prince William even before his wedding to Meghan Markle in May 2018.

According to a new book, "Brothers and Wives: Inside the Private Lives of William, Kate, Harry, and Meghan," the Duke of Sussex shouted at his elder brother when the latter raised concerns that he was moving too fast in his relationship with the former American actress.

"Prince Harry was so incensed when his older brother, Prince William, questioned his fast-moving romance with Meghan Markle that he blurted out, 'Who the hell do you think you are?'" author Christopher Andersen wrote, as per Page Six.

Anderson said that the alleged outburst, revealed to him by a palace insider, happened in September 2017, a year after Harry started dating the "Suits" alum. It was after Harry told his brother that he is planning to propose to Meghan. Harry's announcement prompted the Duke of Cambridge to ask, "Why rush things?"

As per the book, William was not the only person who was concerned that Harry and Meghan were moving too fast. Princess Diana's brother Charles Spencer was also skeptical of his nephew's decision, and was drafted by William to underscore his opinion that the lovebirds should slow down. However, Harry got "furious that his brother was actively seeking to have others interfere in his personal affairs."

The book, that is scheduled for a release on November 30, also dissects the one-time close bond between Harry and William and the ongoing drama that allegedly caused its collapse. The author writes that Harry's relationship with Meghan was a huge factor behind it, as he started getting "angry" with anyone he perceived to be "against Meghan."

Harry had already hyped up Meghan to William before introducing them, as he was worried that his brother, who can be "very stiff," would think her "an opportunist." After the meeting, William was initially charmed, but soon harboured doubts.

Andersen writes that William and wife Kate "wanted a proper English rose" for Harry, and headlines about Meghan and her father Thomas Markle made them anxious. The Duke and Duchess of Cambridge were particularly "alarmed" by the statements against Meghan given by her own half-siblings Samantha and Thomas Jr.

William, Harry, Meghan Markle and Kate Middleton
Prince William, Prince Harry, Meghan Markle and Kate Middleton. Photo by: Paul Grover/AFP/Getty Images Paul Grover/AFP/Getty Images