Prince Harry and ex-girlfriend Cressida Bonas are rumored to be back in each other's arms.

However, the prince's sister-in-law, Kate Middleton is not happy with this bit of news, according to Life and Style via "OK!" magazine.

"Kate doesn't like Cressida at all," the insider told Life and Style. "It's not just that she thinks Cressida isn't a love match for Harry. It goes deeper than that. She doesn't want her in the family."

The insider disclosed that Middleton's antagonism towards Cressida Bonas could be due to the alleged fling Prince Harry had with the British actress' half-sister Isabella Anstruther-Gough-Calthorpe.

William was reportedly linked to Anstruther-Gough-Calthorpe during the time the prince was still single and broke off from Middleton.

The source said that the thought of having Cressida Bonas as part of the royal family has made Kate apprehensive, as she is "afraid that William sees Isabella as the one who got away."

According to the source "Kate hates even hearing Isabella's name mentioned," adding, "She was obviously upset when Cressida and Harry started dating."

The source further disclosed that Middleton is worried that Cressida Bonas might hurt Prince Harry once again since it was the former who initiated the pair's break-up.

"Kate's even told William to warn Harry against her," said the source. "She does not trust Cressida."

In the meantime, Cressida Bonas, the ex-flame of Prince Harry, will grace the cover of Jalouse magazine's October issue, according to the Daily Mail.

During the shoot, the 26-year-old model-actress posed in an array of 60s inspired designer outfits.

Prince Harry's former beau showed that she could hold her own in front of the camera, as she highlighted her signature look: freckles, a healthy glow and unkempt hair.

Over the past several weeks, the style icon has recently been seen in the company of A-list in during big ticket fashion week parties and events.

This is not the first time that Cressida Bonas has made it on the cover of a major fashion magazine, as the ex-lover of Prince Harry has also appeared in the front cover of Miss Vogue, while also modelling for Vanity Fair and Mulberry.