EXCLUSIVE: Prince William 'Refuses to Forgive Harry After UK Homecoming'

So far, reactions to Prince Harry and Duchess Meghan [Markle]'s surprising return to the U.K. in late August have been decidedly mixed, RadarOnline.com can reveal.

British fans of the polarizing couple are thrilled to have Harry home and fellow Hollywood transplants Ellen DeGeneres and wife Portia de Rossi celebrated the pair's move at a recent pub outing with Markle.

While his late mother's niece, Lady Eliza Spencer, told reporters in August she was "absolutely" excited about her cousin's comeback, Harry's father, King Charles III, released a terse letter stating his son and daughter-in-law would remain "non-working royals" – a missive widely interpreted as a preemptive strike to keep the couple out of the royal embrace.

And Harry's estranged brother, William, 44, has remained silent on the subject. "William's acting like Harry and Meghan don't exist," a source told RadarOnline.com. "Ignoring Harry is his way of handling what he considers to be a wretchedly unpleasant situation."

Harry, 42, isn't taking kindly to being iced out. "It's infuriating to him," the source said, noting the younger sib has reached out to William's aides in the hopes of setting up a sit-down to clear the air, but has received no response. Now, he's running out of patience.

Said the source: "Harry's known to be impulsive, and the more wound up he gets, the more likely he is to follow through on threats to make William regret this."

William has not recovered from Harry airing the royal family's dirty laundry after leaving The Firm in 2020. The source said Harry has apologized to no avail. "He insists he's tried to find every possible way to say that he's sorry," said the source. "He's genuinely shocked that there's not even been a shred of forgiveness on William's part."

Charles, 77, is eager for his children to mend fences, if for no other reason than to protect the reputation of the monarchy. "The king has given the orders for this feud to be squashed, but as everyone knows William is refusing to come to the table," the source revealed.

Harry and Charles last met when he and Markle and their kids, Archie, 7, and Lilibet, 5, joined the king and Queen Camilla, 79, at their Highgrove House estate in July.

"William is openly going against the king's wishes by acting as though Harry and Meghan are banished," said the source, "when they're clearly right at his doorstep."

William's wife, Princess Kate, also 44, is pushing the king's agenda. "Kate is desperate to find a compromise that will end this ugliness," said the source. "She wants peace and hates the fact that the monarchy is suffering. She's also saddened to see her husband at war with his own flesh and blood. After all, they used to be so close."

As RadarOnline.com previously reported, Meghan has not been thrilled about upending her life in Montecito, Calif., and moving back to England. While Harry fumes about William, the former Suits star has been acting like it's business as usual, setting the kids up at school and pursuing her work projects.

"A lot of people think she's playing the long game and that her heart is still very much in California," explained the source. "She's doing what she has to for Harry's sake." On Oct. 6, she launched a new holiday collection for her lifestyle brand As Ever in an Instagram post featuring her baking cookies and making jam with Lili.

"She's been throwing herself into work nonstop since arriving in the U.K.," the source said, adding, "She's very clear that it's her priority."

Like Charles and Princess Kate, courtiers are pushing for a truce between the brothers – before the 30th anniversary of their mother Diana's tragic death in August. "They fear the Sussexes could make things seriously ugly if tensions are allowed to continue," the source said.

To that end, palace power players are trying to get the brothers to work together on a tribute for their late mom, in hopes their love for her will bring them together.

William "has refused," the source says, and in early October, media personality Piers Morgan opined that the chances of a joint project are highly unlikely given the fact that William remains "absolutely incandescent with anger" at his brother. (Harry is in talks to do a Diana documentary on his own, per a spokesperson.)

No one would be more heartbroken over their rift than Diana.

"She would be devastated," said the source. "There's no question."