CREDIT: Facebook/Royal Gossip

Despite dating Prince Harry since 2012, Cressida Bonas is yet to meet her boyfriend's sister-in-law Kate Middleton leading fans of the royals to believe it's because of Chelsy Davy.

The Zimbabwe-born Davy and the Duchess of Cambridge have had time to bond when the two were still royal girlfriends, insiders say but by 2009, the Daily Mail wrote that Davy and Middleton are no longer friends.

A friend of Kate and Chelsy told the Daily Mail that, "When they last saw each other Kate told Chelsy not to make such a fuss about Harry being away."

The now Duchess of Cambridge also reportedly told Davy to "ignore rumours he [Harry] was playing around." The friend reveals, "Kate's thoughts were that it comes with the territory." Chelsy Davy was invited to Kate Middleton's big day as Prince Harry's plus one.

Although there is a rumoured rift between Chelsy and Kate, rumours that Kate Middleton prefers Chelsy Davy over Cressida Bonas are still making the rounds.

The real reason for the "friction" according to "Kate: The Future Queen" writer Katie Nicholl is because of Cressida Bonas' half-sister Isabella Calthorpe. Calthorpe, an actress and one of the daughters of Lady Mary-Gaye Curzon, was reportedly pursued by Prince William in 2007 during his brief break up with Kate Middleton.

Nicholl added that the prince had strong feelings for Calthorpe back in 2004 when the Duchess of Cambridge was already in the picture.

According to EntertainmentWise, Kate Middleton was allegedly so intimidated by the aristocrat Isabella Calthorpe that "she banned the prince from seeing her again."

Cressida Bonas is very close to her sister Bella, sources say. EntertainmentWise also notes that if indeed a wedding is in the works, Cressida Bonas's sister Bella will likely be the matron of honour. The magazine reveals that the scenario will be the Duchess' "worst nightmare".

Many of Kate Middleton's fans are also not fond of Cressida Bonas. One fan says Prince Harry should choose Chelsy Davy over Cressida Bonas because "she was here from the beginning."