"OK" reports that Spare has "dealt a blow to Prince William and Kate Middleton's relationship" and is "increasingly upset that her husband is not fighting back against her brother."

"Kate felt that William should be doing more for her," said one source. 'But William and the Palace thought it best not to say anything.'

In his memoir, Harry claims that Kate made his wife Meghan Markle cry during an argument before their 2018 wedding, and also claims that both William and Kate found Harry's Nazi costume scandal amusing.

Royal writer Tom Quinn has stated that the Prince and Princess of Wales often quarrel, but only behind closed doors (for example, "Marie Claire" recently reported that the couple are currently at odds over the role of their oldest son, Prince George, in King Charles' next coronation (For example, Marie Claire recently reported that the couple are currently at odds over the role of their eldest son, Prince George, in King Charles' next coronation.)

"Someone at the palace told me about the nicknames they have for each other," Quinn said. 'But it's not all that sweet. They get into terrible fights where they throw things at each other. Kate and William may seem like very calm people. But that is not always the case. The great stress for William and Kate is that they are constantly surrounded (by the palace entourage). It's like something out of a Jane Austen novel."

According to Quinn, despite the "shouting matches," Kate always manages to smooth things over with William.

"Kate is a very calm person. William is a little hotheaded. Kate is very calm. She's the one who tries to pour oil on troubled waters and try not to stir things up."

A source added, "Kate has a Zen-like presence and a way of softening things up. When William and Kate married, they took their vows to heart. They are both proud of their marriage and hope it lasts."