"It is well known that Kate and Rose have had a terrible falling out. They used to be close but that is not the case any more," an insider alleged to the publication.
Word around the palace was that Kate was adamant on phasing Rose out of her social circle, while William was attempting to "play peacemaker" due to the two women sharing many mutual friends.
But Will's reported attempts to diffuse the situation appeared unsuccessful at the time, as the Daily Mail claimed that both parties were considering taking legal action.
Things then went downhill faster than a corgi when British socialite and food critic Giles Coren tweeted: "Yes. it is an affair. i haven't read thee piece but i know about the affair. everyone knows about the affair, darling. even us jews. (although admittedly i'm quite a posh jew – if such a thing exists."
The Times food critic, however, has a reputation for stirring the pot (no pun intended), and quickly deleted the tweet. The accusations themselves have also been denied by many royal experts over the years.
“William and Kate came out stronger than ever, the couple realising if any proof were needed, that this was the price of a life spent in the public eye." Andrew Morton told us.
So who was the woman alleged to be William's mistress? Scroll on to find out everything we know about Rose Hanbury.
Who is the woman behind Prince William's alleged cheating scandal.
Marchioness Rose Hanbury was born on March 15th, 1984, making her 37 years old. She is married to David Rocksavage, the 7th Marquess of Cholmondeley.
The pair wed in 2009 at Chelsea Town Hall and, according to a report from Hello!, it was a whirlwind engagement indeed.
"In June 2009 the couple announced their engagement, the next day it was revealed they were expecting and just a day later they tied the knot." the publication revealed.
Rose and David share three children together: twin boys Alexander and Oliver, as well as a daughter named Iris and live at the Houghton Hall estate in Norfolk, which happens to be right around the corner from Kate and Will's country home, Anmer Hall.
The 37-year-old mother-of-three is constantly capturing stunning photos of the estate's gardens and sculptures which she then shares to her personal Instagram account, as well as a special one she made just for Houghton Hall.
Rose's ties to the royals run deep within her blood.
Rose's ties to the royals run deep within her blood, starting with her grandmother - Lady Elizabeth Lambart - who was one of The Queen's bridesmaids when she wed Prince Philip.
While the brunette once worked as a model, she and Kate apparently grew close through their charity work with East Anglia's Children Hospice.
Rose and Kate apparently grew close through their charity work with East Anglia's Children Hospice.
Despite the cheating rumours that sent shockwaves around the world back in 2019, both women remain married to their respective partners and seem happier than ever.