In the aftermath of Meghan and Harry's royal wedding, rumours began to circulate that the newly minted Duchess had reduced her sister-in-law Kate Middleton to tears during an argument over Princess Charlotte's bridesmaid dress.
While the exact reason for the fight remains unclear, the Duchess of Cambridge and the American-born former actress are said to be very different people - though Kensington Palace continues to dutifully deny rumours of a rift between the wives of Windsor.
Tensions also mounted in the lead up to Meghan's nuptials to Prince Charles and Princess Diana's youngest son, after Queen Elizabeth II reportedly vetoed her first choice of bridal tiara.
It was one of many fraught royal wedding conversations, which, according to royal biographer Robert Jobson, left Harry shouting at staff:"What Meghan wants, Meghan gets!"
In recent weeks, whispers of a royal rift between the Cambridges and Sussexes have only intensified and the royal couple's "united" appearance at Trooping the Colour in London earlier this month did little to quell speculation.
Buckingham Palace insiders say tension has reached breaking point after Prince Harry and Meghan abruptly pulled out of the Royal Foundation last week - a joint charity founded by Prince William and Harry in 2009.
“You could cut the tension with a knife,” says our well-placed source of the foursome’s recent encounter, adding that away from the cameras, Harry and Meghan "barely uttered two words to William and Kate."
Meanwhile, royal author Phil Dampier, who has been writing about the royal family for over 30 years, has also expressed his concerns.
"The decision to split their offices is a mistake,” Phil says of Prince Harry and Meghan Markle's decision to break from Kensington Palace.
“Harry and Meghan want to use Instagram and other social media to get their messages across, and in that sense, they are in tune with the younger generations.
“But they mustn’t neglect older people in their haste to appeal to younger people.
“Queen Elizabeth and Prince Philip have more than 1500 patronages between them.
“Who is going to take them all on? The last thing the Queen wants is for her life’s work to fall apart after she’s gone.”