Prince Harry's Relationship With Prince William, Kate Middleton Became 'Disruptive' When Meghan Markle Joined: Royal Expert

Prince Harry's close bond with his big brother, Prince William, and sister-in-law, Kate Middleton, changed when he married Meghan Markle, according to a royal expert.

Ingrid Seward, a royal biographer and editor of Majesty magazine, weighed in on the Sussexes' relationship with the Waleses. She looked back at how tight Prince Harry's relationship was with Prince William and Middleton. The three royals were always together and were dubbed "the royal trio."

"It's something that I could see," Seward told Fox News Digital. "Kate, Harry and [Prince] William were a really close-knit trio. ... They all got on really well. And Harry was constantly around at Kensington Palace having supper with them, borrowing things from their fridge."

RELATED: Prince Harry Is Causing Tension In Marriage By Pressuring Meghan Markle To Join UK Trip, Royal Expert Claims

According to Seward, the chemistry that Prince Harry had with the Prince and Princess of Wales changed when Markle joined the picture. Prince Harry would usually introduce his girlfriends to Middleton, but there was an apparent lack of warmth between the two duchesses from the get-go.

"Every time he had a new girlfriend, the first person that would meet her would be Kate," the "My Mother and I" author said. "And then Meghan came into the mix, and it was disruptive. It wasn't like the other girlfriends. There [wasn't] that warm feeling. I think it started on the wrong foot."

"Kate wanted to like Meghan, but it didn't work out that way," Seward continued.

Seward previously told The Telegraph when she promoted her recent book "My Mother and I" that "maybe Harry was a little in love with Kate." She, however, clarified that it was a different type of love because King Charles' youngest son allegedly wanted a sister.

RELATED: Prince Harry, Meghan Markle Quietly Downgraded On Royal Website

"I don't mean physically, but mentally," she told the outlet. "He always longed for a sister; he told [his mother, Princess] Diana that. Psychologically, I think he just adored her, and he was always there, at Kensington Palace, in their fridge, you know, 'What's for supper?'"

Due to Prince Harry and Middleton's closeness, Seward was convinced that the former "Suits" star had been "incredibly envious and then jealous of Kate." Markle's jealousy could also be due to their disparity in the monarchy as Middleton will be the Queen of England when her husband, Prince William, ascends the throne.

"I heard Meghan actually thought she was going to be a princess and live in Windsor Castle. Instead, there's William and Kate with this beautiful house, while they are stuck in Nottingham Cottage, which Harry used to call 'my hovel,'" Seward said.

The Waleses and Sussexes are reportedly not on speaking terms at present. Many thought that Prince Harry and Markle could mend the fences with the royals following King Charles and Middleton's cancer diagnosis.

Tom Quinn, a royal biographer and author of "Kensington Palace: An Intimate Memoir from Queen Mary to Meghan Markle," claimed that Prince Harry wanted to reconcile with his father and sister-in-law. However, he couldn't allegedly get his wife, Markle, on board, as she was still waiting for the royal family's apology.

However, the Duke and Duchess of Cambridge reportedly have no plans for a reconciliation. Sources close to the Waleses said their "Harry problem" was the last thing on their mind amid the King and Princess of Wales' health battles.