Prince Charles and Princess Diana
Prince Charles realized that Princess Diana upstaged him when visitors came to see her and not him. Pictured: Prince Charles and Princess Diana watch an official event during their first royal Australian tour 1983 in Newcastle Australia. Getty Images/Patrick Riviere

Prince Charles realized that Princess Diana had already upstaged him when a certain incident happened.

The late Princess of Wales used to be a shy girl. However, she transformed into a figure who was well-loved by the public after her royal wedding to Prince Charles. She became the most photographed and talked-about personality to the point that her husband felt he was overshadowed.

"[Diana] sort of metamorphosed into a very, very elegant blonde beauty. They did a visit to Wales which was the beginning of, for Prince Charles, realizing, 'They've come out to see my wife, they haven't come out to see me,'" Lady Elizabeth Anson, a party planner and a cousin to the Queen, told People.

The publication noted that Prince Charles' jealousy didn't end with Princess Diana; it continued to their eldest son, Prince William, especially after he married Kate Middleton. The heir reportedly felt that the Duke and Duchess of Cambridge were a threat to him.

"Charles saw Kate and William as the new stars and feared he'd be in trouble," Robert Higdon told Tom Bower in unauthorized biography "Rebel Prince: The Power, Passion and Defiance of Prince Charles."

Princess Diana and Prince Charles had a rocky marriage. In fact, the People's Princess was heard saying that their marriage was crowded as there were three of them. The late Princess of Wales was apparently speaking about Prince Charles' affair with Camilla Parker Bowles.

Prince Charles and Camilla dated before they married their ex-spouses Princess Diana and Andrew Parker Bowles. However, they broke up when the prince went abroad for an overseas duty. In addition, the royals reportedly didn't approve the Duchess of Cornwall for Prince Charles.

According to Sally Bedell Smith's biography "Prince Charles: The Passion and Paradoxes of an Improbable Life," Prince Charles didn't marry Camilla in the first place because she was perceived as an "experienced" woman. Also, Camilla was not "aristocratic" enough for the future king.

However, Prince Charles and Camilla's respective marriage eventually ended in divorce and they reconciled and got married. According to Paul Burrell, Princess Diana suspected her husband of plotting a mobile accident to kill her and eventually remarry.