Parents impart wisdom to their children whenever they can, and it seems that Prince Charles is no exception.

According to royal expert and author Ingrid Sward, Prince Charles had a heart-to-heart with his eldest son, Prince William, before his wedding to Kate Middleton, and cautioned him to avoid the marriage mistakes Prince Charles himself made.

“My father said, ‘Look, William, nothing is more important than family,’” Sward told the New York Post.

While the idea that family is most important may sound a bit generic, Sward claims that Charles also gave him more personal advice.

“‘Don't make the same mistakes I made,’ Charles told Will,” Sward said. 'I just did my duty, duty, duty. I just did my duty, my duty, my duty.'

Charles has been happily married to Queen Camilla (who was Duchess of Cornwall before Charles became king) since 2005, but his first marriage to Will's late mother, Princess Diana, was notoriously troubled, and the king's advice seems to refer to mistakes made during that marriage

Indeed, by the time Prince Charles and Princess Diana decided to end their marriage, things had gotten so bad that, according to a report in the Express, when the two visited South Korea in November 1992, “hatred swirled between them,” according to a reporter covering the story. [Prince Charles and Princess Diana officially announced their separation a little over a month later, in December 1992. 15]

Longtime royal photographer Arthur Edwards later said that during the couple's tour of Korea, they were “miserable” with each other and it was clear that their marriage was ending.

He said.

“When we went to Korea, on our last tour, it was the only time we knew it was all over because we couldn't stand being with each other. It was so miserable,” Edwards said. 'That tour was called the Grumms tour, and it was so miserable. Then, a month later, the prime minister announced it in the House of Commons. I don't think anyone was surprised at the time, but we were watching them in Korea.”

After the separation, Diana began to experience loneliness and talk about feeling neglected in her marriage (such as in a controversial 1995 interview with the BBC's Panorama, in which she discussed her affair with Charles and his current wife, then known as Camilla Parker-Bowles), For years, royal experts have pointed to Charles' prioritization of duty over Diana's feelings as a key issue in his relationship with her.

Elizabeth Holmes, author of HRH: So Many Thoughts on Royal Style, told Us Weekly that the marriage between Prince Charles and Princess Diana was “almost like a business transaction,” and that the Prince at the time was most attracted to Princess Diana Princess Diana may have been the one he was most attracted to at the time.

Holmes also noted that their courtship was notably short (Prince Charles met Diana only twice when he began romantically pursuing her in July 1980, just one year before they were married in a lavish royal wedding in July 1981) As for “It kind of speaks to how [Prince Charles] was approaching this and the pressure he was feeling.... It was almost like a formality.”

It is not clear whether Prince Charles directly encouraged Will to have a short engagement, but the prince was determined not to repeat that mistake in his own marriage and took the opposite approach in his relationship with Kate Middleton, whom he had dated for almost a decade before asking the question.

According to royal author and expert Katie Nichol, Will took things slowly to avoid putting Kate in the same position as her mother by rushing the royal marriage.

“Before William asked Kate to marry him, he wanted to make sure that was what she really wanted. By living together, Kate could decide whether or not she was, and if not, she could 'back out,'” William later recalled.