Meghan Markle is thought to be behind the friction between the two princes which has led to the Sussexes deciding to step down as senior royals and move to Canada.
The Queen sees keeping Princes William and Harry on good terms as crucial for the future of the Royal Family.
Meghan Markle and Prince Harry’s decision to step down as senior royals and move to North America shows how the relationship between the two brothers has broken down.
The pair have been to see the Queen at Sandringham with the monarch wanting them to sort out their differences that are thought to stem from Harry’s relationship with Meghan.
William and Harry were known for their bond following the death of Princess Diana and they jointly backed causes like the Invictus Games.
Now, that unity has gone with William admitting he is sad about the situation.
He told a pal: “I’ve put my arm around my brother all our lives and I can’t do that any more. We’re separate entities.”
A source said their rift stems from William warning Harry not rush into marriage with Meghan which the younger brother saw as an attempt to “clip his wings” and he reacted with “typical petulance”.
Kate has tried to play peacemaker by arranging visits to see Harry and Meghan at their new home in Windsor.
And William has expressed hope he and his brother might pull together again but is clear Harry is determined to seek a different life.
William reportedly also told his close friend: “I’m sad about that. All we can do, and all I can do, is try to support them and hope that the time comes when we’re all singing from the same page.
“I want everyone to play on the team.”
One well-placed insider said: “Much of this situation stems from the breakdown in Harry and William’s relationship. From being so close and supportive of one another for years, they’re moving in such different circles it’s hard to see them repairing the damage.
“Even before the split in their households in 2018 the cracks were there.
“Harry was still trying to find his way after leaving the Army but also found it odd he was having to play second fiddle to William on so many things, especially when exploring his options for charity and patronage roles.”
The insider said Meghan’s disregard for protocol had initially been seen as refreshing and exciting but is now largely regarded as discourteous.
They said: “This has unfortunately all contributed to the perfect storm, emboldened by Harry and Meghan’s insistence to move too quickly to try to have the upper hand. Now the senior members of the family are left to pick up the pieces with the Queen and Charles agreeing that the brothers’ relationship must be salvaged for the sake of the monarchy’s standing across the globe.”
Harry and Meghan are also understood to have told Sir Elton John and TV star Oprah Winfrey that they intended to step down before informing the Queen and Charles, further angering the senior royals and their staff.
They only alerted Her Majesty minutes before telling the public they want to divide their time between the UK and Canada and work towards being financially independent.
The royal household fears the couple could end up quitting for good, which would be an “utter tragedy” according to Charles. So senior royals are considering offering the couple a high-profile Commonwealth role in a bid to keep them as part of the team. But Harry and Meghan are said to be “philosophical about the prospect of losing their titles”.
The Queen wants to come up with a concrete plan which allows them to “step back” without further damaging the monarchy.
She appeared downcast as she arrived at church in Sandringham yesterday, while husband Prince Philip, who has not long been discharged from hospital, was said to be livid about the latest crisis.
Harry is expected to leave the UK on Thursday after hosting the Rugby League World Cup draw at Buckingham Palace.
A source said of today’s crucial showdown: “This is a once-in-a-generation meeting and depending how it goes could have consequences which would echo for decades to come.”