Prince Charles reportedly broke Princess Diana’s heart due to a “stupid” decision.

The Prince and Princess of Wales had a fairytale wedding. However, their marriage wasn’t as smooth-sailing. In fact, there was already tension between even during their honeymoon.

In Channel 5’s documentary “The Royal Family at War,” royal experts criticized Prince Charles for making a poor choice during his honeymoon with Princess Diana. “Charles did not show huge emotional intelligence if I’m brutally honest,” royal biographer Penny Junor said.

Junor was referring to Prince Charles' decision to wear the cufflinks that Camilla Parker Bowles gave him during his and Princess Diana’s honeymoon. The cufflinks featured two C’s entwined that reportedly represent their names. In addition, he hurt the People’s Princess by bringing a picture of Camilla.

“It’s hard to believe that anyone as intelligent and as well-read as the Prince of Wales could be so stupid, so utterly unable to imagine what a new wife might conclude if her husband carried a photograph of his old girlfriend in his diary, or chose to wear cufflinks bearing her initials, when he must’ve had dozens of others to choose from,” Junor wrote in her book “The Duchess: The Untold Story.”

Princess Diana reportedly confronted Prince Charles about the cufflinks, and he admitted that they were from Camilla. However, the Prince of Wales insisted that there was nothing wrong about him wearing them because they were a present from a friend.

Princess Diana’s butler, Paul Burrell, admitted that the cufflinks really affected Princess Diana. In fact, years after their honeymoon, Princess Diana asked him to pick off all the C’s of her Chanel shoes and handbags. Burrell said that Prince William and Prince Harry’s mom “couldn’t bear“ to see two C’s entwined.

Prince Charles and Princess Diana’s honeymoon had reportedly been a disaster. The Princess of Wales was reportedly not happy with her husband sitting for hours in front of his easel.

One time, the future king was painting on the veranda deck and went off to look at something for half an hour. When he returned, his painting and art materials were all destroyed by Princess Diana.

Just recently, twin psychics claimed that Princess Diana spoke from the grave. Prince William and Prince Harry’s mom has reportedly already forgiven Prince Charles and Camilla.

Princess Diana and Prince Charles
Princess Diana and Prince Charles at the Chelsea Flower Show, London, May 1984. She is wearing a navy maternity coat by Jan van Velden. Getty Images/Jayne Fincher