Relations between the pair are not said to have been the same since the brothers fell out the night before their two families appeared in public for the first time with baby Archie.
William and Harry played in the King Power Royal Charity Polo Day at Billingbear Polo Club in Berkshire on July 10.
New mum Meghan attended with Archie, while Kate cheered William on from the sidelines with their kids Prince George, Princess Charlotte and Prince Louis.
However, a senior royal source told The Sun the brothers had argued the night before the match.
The source revealed: "It’s absolutely heartbreaking to see just how damaged William and Harry’s relationship has become."
They added: "They’ll always love each other as brothers, but right now things have never been so bad. William feels betrayed and let down by Harry."
They’ll always love each other as brothers, but right now things have never been so bad.
The source continued: "Harry feels like William and Kate never gave Meghan a chance. And now they’re leaving the country in this state."
The royal rift is said to have started when William told Harry to heed their mother's advice about not marrying in haste.
Prince Harry fuelled rumours of a rift with William when he appeared to address the fall-out in his African Adventure documentary.
He told the cameras: "Look, we’re brothers, we’ll always be brothers. And we’re certainly on different paths at the moment, but I’ll always be there for him, as I know he’ll always be there for me."
Harry added: "We don’t see each other as much as we used to because we’re so busy, but I love him dearly . As brothers, you know, you have good days, you have bad days."
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