EXCLUSIVE: Kate Middleton Risking Her Marriage By 'Secretly Betraying Prince William' With This One Shocking Vow to Dying King Charles

Kate Middleton has made a solemn vow to King Charles — and it’s one her husband may never forgive, palace sources tell RadarOnline.com.

"Kate has promised Charles she’ll do everything she can to bring everyone together," a royal insider told us. "She believes time is running out, and she’s not going to stand by and let this family fall apart."

The 43-year-old Princess of Wales has reportedly pledged to help heal the bitter rift between Prince Harry and the rest of the royal family — despite Prince William’s ongoing refusal to engage with his brother.

Cancer-stricken King Charles, 76, is said to be relying heavily on Kate to broker peace, even as he battles cancer and updates his funeral arrangements.

According to a well-placed source, this private pact between the King and his daughter-in-law could be seen as a betrayal by William, 43, who remains staunchly opposed to any reconciliation.

"Charles has had enough of the fighting," a source said. "He wants Harry back in the fold before it’s too late, and he sees Kate as the key to making that happen. William isn’t on board, but Charles believes Kate can change his mind."

The news comes as funeral plans for the King, known internally as Operation Menai Bridge, are reportedly being revised — and include a prominent role for Harry, 40, and Meghan Markle, 43.

Despite stepping down from royal duties in 2020 and relocating to California, the Sussexes are expected to take part in the London procession, family vigil, and funeral service.

Their children, Archie, six, and Lilibet, four, have also been included in the arrangements, should they choose to attend.

Kate’s relationship with Charles has deepened in recent years, particularly after both were diagnosed with cancer.

In January 2024, they were treated at the same London clinic and later shared a private lunch at Windsor, during which Charles reportedly had an "emotional" heart-to-heart with his daughter-in-law.

The King later praised Kate for going public with her diagnosis, saying he was "so proud of Catherine for her courage in speaking as she did."

"Kate sends him care packages and checks in on him constantly," an insider said. "Charles respects her more than anyone else in the family. He sees her as the glue holding them together."

But the royal family’s fractures are running deeper than ever.

Tensions between the Sussexes and the rest of the royals began in the run-up to Harry and Meghan’s 2018 wedding, when reports emerged that Meghan had made Kate cry.

Markle later claimed in a 2021 interview that it was the other way around and that the Palace had allowed the false version of events to circulate unchecked.

The feud worsened with the publication of Harry’s 2023 memoir, Spare, in which he alleged William physically attacked him during an argument over Meghan, calling her "difficult, rude and abrasive."

The brothers have barely spoken since.

Last month, Harry reignited tensions by revealing in an interview that his father wasn’t speaking to him. "I don’t know how much longer my father has [left]," he said, while adding: "It would be nice to reconcile."

Our source said: "Harry is ready to make peace. He knows the clock is ticking. Kate believes he and William will regret it forever if they don’t fix this now."