• Queen Elizabeth was initially always excited to take Prince Harry's phone calls
  • She eventually grew "perplexed" by his constant complaints
  • Many in the royal family were infuriated by Prince Harry's direct correspondence with the Queen

A royal expert has revealed how the bond between Queen Elizabeth II and Prince Harry soured after the Duke of Sussex moved to the U.S. with Meghan Markle.

According to Richard Kay, the late monarch shared a "close bond" with her grandson until the beginning of his time in the U.S., but things changed when she grew tired of Prince Harry's complaints.

Kay said after the Duke and Duchess of Sussex stepped down as senior working royals and left the U.K., the queen was always excited to take Prince Harry's phone calls. However, she eventually grew "perplexed" by his constant grumbles.

"The Queen's staff have told me how, in the early days of Harry's exile in America, the Queen would excitedly take his phone calls," he said. "Over time this changed and she later became perplexed by Harry's complaints."

The royal expert also revealed how Prince Harry's direct correspondence with his late grandmother did not sit well with the other members of the royal family. According to Kay, Prince Harry always took the "route-one approach" when he had issues, going straight to the queen to air out his complaints. This allegedly "infuriated other senior royals," causing the rift between him and them to grow deeper.

Prince Harry's unique bond with Queen Elizabeth II is not new to many. Throughout the turmoil caused by his and Meghan's departure from the U.K., the Duke of Sussex made sure his relationship with his grandmother remained intact.

Despite the highly publicized royal rift, Prince Harry kept the queen up to date on his life and family. Back in April, he also dropped in on Queen Elizabeth at her home in Windsor Castle, while he was on his way to the Invictus Games in The Netherlands. He also opted to name his daughter Lilibet, in honor of Queen Elizabeth.

In an interview with ET Canada, King Charles' former butler described Queen Elizabeth's relationship with her children and grandchildren as "amazing." He said, because of that, it was sad the monarch died before the rift between Prince Harry and Prince William was fully resolved.

Queen Meghan Markle Prince Harry
The Queen reportedly stopped Meghan and Harry from having an independent household. Queen Elizabeth II, Meghan, Duchess of Sussex, Prince Harry, Duke of Sussex are pictured on July 10, 2018 in London. Chris Jackson/Getty Images