A lot might have happened during Prince Harry and Meghan Markle's U.K. visit for the celebration of Queen Elizabeth's Platinum Jubilee without the public knowing. Aside from an alleged secret meeting with Prince Charles, Prince William reportedly feels upset with how his relationship with his younger brother has deteriorated.

A friend revealed, via Express, that Prince William "feels let down" over his relationship with Prince Harry. In fact, the two Princes didn't have the chance to spend some private time during the Duke of Sussex's return to the U.K.

Though the two both attended the televised Service for Thanksgiving at St. Paul's Cathedral, they never greeted each other in public. The Cambridges were also invited to Lilibet's first birthday party at Frogmore Cottage on Saturday, June 4, but they were in Cardiff for a Jubilee appearance.

Anyhow, they wished the kid a happy birthday on Twitter. "Wishing a very happy birthday to Lilibet, turning one today!" the @KensingtonRoyal page tweeted.

Prince Harry and Meghan Markle reportedly left the U.K. before the Jubilee celebration officially ended. It was their first major royal event joint outing after stepping down as senior royals in 2020.

During their stay in the U.K., they allegedly had a secret meeting with Prince Charles. The royal couple was said to be expecting "peace" with the royal family but left disappointed as there were no "touchy-feely vibes" toward Prince Harry.

Royal commentator Christopher Anderson told "Royally Us," via Mirror, that the Sussexes held a "perfunctory meeting" with the Prince of Wales during the Jubilee celebrations and hoped for a "rapprochement" with the royal family. He said the curtain had evidently come down on the possibility of harmony between the father and son.

He added Princess Diana would be "heartbroken" with the state of the relationship between the two and Prince William. Anderson continued that the late People's Princess would have understood why his youngest son wanted to have his own life away from the monarchy and build a new one with his own family in California.

But the Princess of Wales always saw Prince Harry as Prince Williams' wingman, often saying her boys were her "revenge." She meant that they should have worked as a team and would go on and carry the monarchy forward into a more modern era.

However, with how things are going on with the royal family's relationship with Prince Harry today, it looks like the future of the realm will be all about Prince William, Kate Middleton and their kids, Prince George, Princess Charlotte and Prince Louis.