The Duchess of Cambridge was widely reported to have been reduced to tears during a fitting for Princess Charlotte's bridesmaid dress thanks to American-born Meghan's demanding behaviour, which has since earned her the cruel nicknames "Me-Gain" and "Duchess Difficult" from Buckingham Palace staff.
A senior member of the royal family even dubbed the former actress "the degree wife", because the Windsors only expect her to remain married to Prince Harry for three years, the Sunday Times reveals.
Worrying reports also suggest the Duke of Edinburgh was less than enamoured with his grandson's decision to marry a Hollywood celebrity.
"One steps out with actress, one doesn't marry them," Prince Philip allegedly told Harry.
The Duchess of Sussex has been accused of changing her husband for the worse and being responsible for the fractious relationship between her and sister-in-law the Duchess of Cambridge.
The wives of Windsor are said to be "very different people", though Kensington Palace continues to dutifully deny rumours of a rift.
But no amount of denials will quiet the now-obvious fact that all is not well in the houses of Cambridge and Sussex.
With Harry and Meghan living at Frogmore Cottage with baby Archie Harrison and William and Kate hopping between Kensington Palace and Anmer Hall with Prince George, Princess Charlotte and Prince Louis, it's increasingly clear the Fab Four are no more.
"Harry is going to forge his own path with Meghan. For years, before he met Meghan, he was the royal gooseberry standing behind William and Kate," Mr Larcombe said.
"He's now a full-time working royal with his wife. He wants autonomy as to what he does, how he does it and how she does it, which is a definite change to how it was 12 months ago," citing Palace sources who call Prince William "quite controlling".
The board of The Royal Foundation are scheduled to meet later today to confirm the split.
Buckingham Palace declined to comment when contacted by the Sun.