King Charles knows a thing or two about marriage. After all, he’s had two of them. While the first marriage was probably doomed from the start, his second marriage is still going strong.

It seems that the King has reflected on his marriage experience and wanted to give his oldest son, Prince William, words of wisdom when it comes to his own marriage to Kate Middleton.

According to royal biographer Ingrid Seward, Charles gave his son marriage advice that sounds almost like a warning. He told William, “Don’t make the mistakes that I made.”

What mistakes does the King think he made? It seems that he thinks he prioritized his work above his relationship with his wife.

Seward told FOX News Digital that Charles told William, “I just did duty, duty, duty. I neglected my marriage, and look what happened.”

Charles gave his son this advice because he wanted his marriage with Kate to succeed, and it seems that William has taken the advice to heart.

One good example of this can be seen this past year, with Kate’s cancer battle. First, in January, she had a “planned abdominal surgery.” Then, she later revealed that it was discovered as a result of the surgery that cancer had been present and she would be undergoing preventative cancer treatments.

While her diagnosis and recovery meant that she stepped away from her royal duties, she wasn’t alone. William also stepped away from his royal duties to support his wife and their three children. It’s probably safe to say that this is exactly what Charles meant when he warned his son to not to prioritize his duties if it meant neglecting his marriage.

Seward explained that Kate has “had fantastic support from Prince William.” She added, “He publicly said it’s been the toughest year that he’s ever had, and it’s been very … difficult. So, we can only imagine how difficult it [really] must have been because William also [had] to reassure their three young children that mummy’s going to be OK. Kids get very worried when they see their parents unwell, especially for such a length of time.”

What’s important to note here is that while William has been a huge support of Kate, Charles has supported William in his support of Kate. Seward explained, “I think it’s been very tough, and he has been an enormous support. And, in turn, he has been supported by his father.”