Prince Charles didn’t tell Princess Diana everything she should’ve known about him before they tied the knot. This shocking claim is explained by a royal biographer.

According to Penny Junor, Prince Charles didn’t tell Princess Diana about his past with Camilla Parker Bowles. He only did so after the late Princess of Wales accepted his proposal.

In the book “The Duchess: The Untold Story,” the royal biographer said that Princess Diana was very friendly toward Camilla during her courtship with Prince Charles. At that time, the mom of two thought that Camilla was just one of Prince Charles’ good friends.

After her engagement to Prince Charles, Princess Diana learned that Camilla was more than just a friend to her future husband. But since they were already engaged, Princess Diana decided to push through with their wedding.

“He came clean after the engagement,” Junor said. “He had not handled things well. It didn’t occur to him that she needed to know before someone else told her. He made a huge mistake,” she added.

One of Prince Charles’ friends agreed that the future king made a mistake by not being completely honest with his future wife. However, the friend also explained why Prince Charles might have done what he did.

“You can sympathize with Diana, oh God yes,” the friend said. “Put that way, he was the architect of the disaster. But you see, I think he feels that different standards apply to him because he wasn’t allowed to marry the love of his life; he had to produce heirs so he had to do this for the nation. Also, he wouldn’t have had the sensitivity. He’s very interested in objective things but not subjective, so he couldn’t have understood the complexities of her feelings.”

Prince Charles and Princess Diana tied the knot in 1981. One year later, they were blessed with a son, Prince William. In 1984, the couple welcomed Prince Harry. The couple’s tumultuous marriage became worse very early on with Prince Charles telling Princess Diana during one of their heated arguments that he shouldn’t have married her.

Prince Charles and Princess Diana Prince Charles and Princess Diana on their last official trip together - a visit to the Republic of Korea (South Korea). Photo by Tim Graham/Getty Images