SUGGESTIONS of a "feud" between Prince William and Kate Middleton, and Prince Harry and Meghan Markle, have been circulating for months.
However, one royal expert believes tensions first arose around the time of the future Duke and Duchess of Sussex's engagement in November 2017.
The couple had met in July 2016 on a blind date in Toronto, before making their first public appearance together in September 2017.
However, according to a new Channel 5 documentary broadcast tonight, William & Harry: Princes At War?, the Duke and Duchess of Cambridge were surprised by the whirlwind romance that saw Harry get down on one knee after 16 months.
"It was all so quick that William and Kate didn't have a moment to get to know Meghan because Harry hardly knew Meghan," explained Ingrid Seward, royal expert and editor of Majesty Magazine.
"And of course William and Kate would have quite naturally thought 'oh she's been married before, she's older than Harry, I hope she's going to make him happy'. Anyone would think that."
In December, The Sun's Emily Andrews exclusively revealed that Harry, 34, went "mental" accusing William, 37, of trying to "wreck relationship" with Meghan, 38.
"I was told by a number of sources that he went ballistic. He said, 'you're trying to wreck this relationship before it's even started'," she explained on the programme.
As royal correspondent Kate Nicholl added: "That was the moment I was told by sources close to the brothers that the dynamics changed.
"There was a shift and it was largely down to Harry resenting his brother.
"Harry supported William from the out-set of his relationship with Kate, and he felt let down that he wasn't getting his brother's full 100 per cent support with his relationship with Meghan."
Earlier this week, we told you how the 'Fab Four' split began when Harry accused his brother and sister-in-law of not supporting Meghan ahead of their wedding.
According to the , the Duke of Sussex started a "showdown" with William and Kate and "read them the riot act" one evening after their kids had gone to bed.
The Duke and Duchess of Cambridge were said to have been caught off guard by Harry's speech, while his then bride-to-be maintained a "stony" silence throughout.
At the time, both couples were living as neighbours at Kensington Palace.
William and Kate took Harry and Meghan a bunch of flowers the next day, and both women went on to attend Wimbledon together.
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We also revealed how Princess Beatrice doesn't need the Queen's permission to get married, unlike Prince William and Prince Harry.