King Charles III is upset about being separated from two of his five grandchildren, a royal expert told Fox News Digital.

Prince Harry and Meghan Markle's two kids were missing from Charles' historic ceremony as the actress stayed behind in California. The decision was apparently made due to the coronation being the same day as Prince Archie's fourth birthday.

Despite the absence of the little royal, King Charles made a toast to Archie in honor of his birthday, the Daily Mail reported.

"Charles knew he couldn't in all conscience praise William's children and ignore Harry's. And it was Archie's birthday, after all," royal contributor Christopher Andersen told Fox News Digital. "The Sussexes' absence on the Buckingham Palace balcony on coronation day had to have been weighing on Charles's mind. How could it not?"

King Charles and Camilla on the balcony

King Charles is upset about being separated from two of his grandchildren, a royal expert told Fox News Digital. (Getty Images)

"Charles is a doting grandpa, and I have no doubt that apart from all the acrimony it pains him to be separated from two of his five grandchildren."

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British royals expert Hilary Fordwich also confirmed the birthday toast.

"King Charles is not sarcastic. King Charles is a loving, genuine man," she told Fox News Digital. "Ask Lionel Richie because Lionel Richie and him have developed a close friendship. And Lionel Richie has said that he has only goodness in his heart."

King Charles III arrives for his coronation at Westminster Abbey, London.

King Charles III arrives for his coronation at Westminster Abbey. (Andrew Matthews / Pool via Reuters)

King Charles and Queen Camilla

King Charles III and Queen Camilla appear on the balcony of Buckingham Palace following the coronation. (Getty Images)

Prince Harry did attend King Charles' coronation, despite speculation he would skip out on the historic event. However, he reportedly went straight to the airport following the coronation and did not appear on the Buckingham Palace balcony.

"Before Megxit, Harry was always front and center, adding his own spark of youthful exuberance and personal charisma to the otherwise mostly drab royal tableau," Andersen said. "The people loved their mischievous rebel prince, and Charles never turned his back on Harry, no matter what kind of trouble he got himself into."

Even if Prince Harry had stayed in town, he wouldn't have been invited onto the balcony due to his status as a non-working royal family member.

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King Charles Camilla and members of royal family on Buckingham Palace balcony

King Charles and Queen Camilla are joined by members of the royal family on the balcony of Buckingham Palace. (Getty Images)

"Harry would have shown up on the palace balcony had he been asked," Andersen said. "But the powers that be that really run the monarchy have convinced Charles to enforce Queen Elizabeth's rule that ‘non-working’ royals do not deserve such special treatment."

"Imagine how much more of an impact there would have been with Harry up there waving to the multitudes alongside his father the king and his brother, the Prince of Wales," he added. "Unfortunately, those who know Charles have described him as ‘weak’ when it comes to bucking the palace bureaucracy – even though he is the boss. So, the standoff between the Sussexes and the rest of the royals continues, even though the king could unilaterally end it in a New York minute."

The Duke of Sussex at the coronation of King Charles III and Queen Camilla at Westminster Abbey

Prince Harry, Duke of Sussex, attends the coronation of King Charles III and Queen Camilla at Westminster Abbey. (Andrew Matthews / Pool via Reuters)

Prince Harry, Duke of Sussex, walks outside Westminster Abbey ahead of Britain's King Charles' coronation

Prince Harry left London shortly after the two-hour coronation ceremony for his father, King Charles. (Reuters / Dylan Martinez)

Prince Harry was reportedly invited to the family luncheon that took place after the coronation, but he chose not to attend. Fordwich called the move by the Duke of Sussex a "huge shame."

"The king has such a huge heart. It is not surprising at all that he has been so forgiving. There are members of the extended royal family that I know well, on the one hand surprised and yet impressed that the king would extend the kind olive branch to invite Harry to Buckingham Palace afterwards," she explained. "And indeed, Windsor Castle because they went to Windsor Castle I know afterwards for lunch. I just think it's such a huge shame that he has squandered another opportunity that was provided to him to heal wounds."

"And I find that sad, and it was Archie's birthday. But millions of children across the globe have their birthday on a separate day when their parents are working or some business or special event," she added. "And a 4-year-old could have had his birthday party one day later, and Harry could have made his father happier."

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Prince Harry and Meghan Markle look serious in a photo

Prince Harry and Meghan Markle stopped being working members of the royal family in 2020. (Getty Images / File)

Prince Harry and wife Meghan Markle stepped back from their roles in January 2020. The move has caused tension between the couple and the working members of the royal family.

The two have participated in a handful of high-profile interviews – one with Oprah Winfrey and a docuseries with Netflix – where they spoke about the royal family.

In the Netflix series, Harry and Markle said the royal family did nothing to help combat the onslaught of negative press that the couple constantly faced.

Prince Harry in a navy suit and tie holds Meghan Markle's hand, wearing a dark dress after the Queen passed away

Prince Harry and Meghan Markle live in California with their two children. (Chris Jackson / File)

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"They knew how bad it was," Harry said during the "Harry & Meghan series. "They thought, ‘Why couldn’t she just deal with it?’ No one would have private conversations with the editors saying, ‘Enough.'"

Since stepping back in 2020, the couple has settled in their California home to raise their two children.