Princess Diana, Prince William, Prince Harry and Prince Charles
Prince William made a lash at Prince Charles for making his mom, Princess Diana, cry. Pictured: Princess Diana, Prince Harry, Prince William and Prince Charles watch the parade march past as part of the commemorations of VJ Day on Aug. 19, 1995. Getty Images/Johnny Eggitt

Prince William wasn’t happy with the way Prince Charles treated his late mother, Princess Diana.

The Duke of Cambridge witnessed the collapse of the Prince and Princess of Wales’ marriage. Prince William saw how they argued and how their disagreements ended with Princess Diana in tears.

According to Katie Nicholl in her 2010 book “William and Harry,” at one point Prince William lashed out at his father during a heated argument. The prince made the bold move because he could no longer bear his parents’ bickering.

“I hate you, Papa. I hate you so much. Why do you make [mommy] cry all the time?” Prince William reportedly shouted at Prince Charles before slamming the door.

The royal author added that Prince Harry’s older brother had been aware of their parents' marital issues. Princess Diana was reportedly dependent on her eldest son that she would regularly confide in him.

There were times when the People’s Princess would sob in her room and Prince William would pass his mother tissues from the other side. Nicholl felt that the incident was a “heavy burden” for the prince who was still so young at the time.

When Prince Charles and Princess Diana decided to finally end their marriage, they first informed their sons. According to Nicholl, Princess Diana made a drive to Ludgrove School to tell her two boys that she and Prince Charles were separating. However, Prince Harry took it very badly. The Duke of Sussex was reportedly very upset.

On the other hand, Prince William understood his parents’ decision right away. He only told his mother that if such a choice would make her happier, then it would be the right thing to do.

Prince William’s reaction didn’t come as a surprise considering the arguments he witnessed. The Duke of Cambridge continued to support his mom all the way until the end.

When Princess Diana’s title was taken away from her following her divorce from Prince Charles, Prince William promised his mom to give it back to her one day when he becomes king.

Paul Burrell is positive that the Duke of Cambridge will fulfill this promise. According to Princess Diana’s former butler, when Prince William becomes the new king, the first thing that he will probably do is restore his mother’s title.