Princess Diana did something that shocked Prince Charles and made Queen Elizabeth II realize that she had enough.

It’s not a secret that the Prince and Princess of Wales had an unhappy marriage. Royal biographer Penny Junor described in her 2005 book, “The Firm,” how Prince Charles and Princess Diana’s ill-fated marriage ended in divorce. She first discussed Prince Charles’ disastrous interview with Jonathan Dimbleby in 1994, when the heir apparent admitted his infidelity to Princess Diana. She then added how Princess Diana took advantage of the situation.

“The reputation of the monarchy was once again dragged through the mire. But there was more to come,” Junor wrote. “Diana nursed her with until it was nicely warm, then she invited the television journalist Martin Bashir into Kensington Palace, who interviewed her for Panorama.”

In her infamous interview, Princess Diana sat demurely with her head bowed. She looked so sad as she wiped the occasional tear that welled.

When asked why her marriage didn’t work, the People’s Princess confessed that “there were three of us in this marriage, so it was a bit crowded.” Upon hearing her statement, Queen Elizabeth II realized that she had enougn.

“The Queen had seen and heard enough,” Junor wrote.

Queen Elizabeth II ordered Prince Charles and Princess Diana to divorce. On the other hand, the Prince of Wales was shocked when he learned about Princess Diana’s interview. The future king was reportedly “completely taken by surprise.”

Queen Elizabeth II and Prince Philip reportedly blamed Prince Charles more for his failed marriage with Princess Diana. They knew that he was already committed to Camilla Parker Bowles even before he married Princess Diana.

Meanwhile, many felt that it was already too late when the Queen and the Duke of Edinburgh intervened in Prince Charles and Princess Diana’s marriage. However, according to Junor, there was a reason why Prince Charles’ parents didn’t intervene on their marital problems immediately.

“Parents of any couple having difficulties in their marriage would be naturally reticent about intervening, uncertain as to whether help would be welcome,” Junor wrote.

Queen Elizabeth ‘Had Enough,’ Prince Charles ‘Shocked’ After Princess Diana Did This Queen Elizabeth II and Prince Charles pose with officers during an official visit to the Household Cavalry mounted Regiment at Hyde Park Barracks on October 24, 2017 in London. photo: Getty images/Chris Jackson