Kate Middleton recently received praise from the public following the success of her hosting a Christmas carol concert. Aside from the applause, she, also, obtained the support of her loved ones, especially Prince William, as well as her parents and siblings.

They were present at the service, and even all smiles for the cameras. However, a source told Life & Style that things "were more complicated than they appeared."

The insider alleged that the Duchess of Cambridge's relationship with Pippa Middleton "has turned frosty." It is all reportedly because the future Queen Consort cannot help but feel "a little envious" of her younger sister.

Kate Middleton allegedly feels "irritated" that Pippa Middleton continues to enjoy the perks of having close links to the British Royals. These include "brand endorsements" and "swanky" parties or engagements.

The informant said that she envies her younger sister being able to have these things even "without any of the responsibilities" of a working royal. She reportedly does all the hard work while Pippa Middleton "lives in a perfect, carefree world."

Based on the claims, the "built-up tension exploded" following their brother, James Middleton's wedding in September. The Duchess of Cambridge is said to have flown into France for the ceremony and gone immediately due to her royal duties.

Amid feeling the exhaustion, the source stated that she "snapped" at her sister, especially after seeing Pippa Middleton "so happy and relaxed."

This reportedly led to a fight between the two personalities, causing them to "ghost" each other for weeks.

In the end, though, the insider asserted that Kate Middleton and Pippa Middleton are now on "better terms." While the relationship is no longer the same, it is said that they are "working through their issues."

Despite all the allegations, the British Royals and the members of the Middleton family have remained silent about the matter. No word has been released yet, so no one can confirm the story.

Moreover, the supposed source did not share evidence to prove the claims. Hence, these all remain as mere speculations about the Middleton sisters' relationship.

Meanwhile, it is true, however, that Pippa Middleton and Kate Middleton are living two different lives today. As the future Queen Consort of the United Kingdom, as well as the mother of the next British Monarch, the Duchess of Cambridge's responsibilities have much wider reach.

In their parenting styles alone, an expert told Express UK that the two women differ greatly in how they raise their respective children. With the Cambridge Royals being more in the public eye, they ensure to be on their best behaviors before the public. Pippa and her kids, on the other hand, are able to be freer to enjoy "without the pressure of constant public attention."