Prince Charles' comment to Diana that sent their marriage 'down the drain'

When the princess was pregnant with the couple's second child, her husband had hoped that they would be welcoming a girl. He was reportedly very disappointed when a second son was born instead.

Diana, Princess of Wales gave birth to Prince Harry on September 15, 1984. She and Prince Charles had decided to keep the gender of their child a secret until the baby was born, so they had not known that they were to have another son.

When Harry was born, Prince Charles gave his baby one look as said, "Oh God, it's a boy." To add insult to injury, he then also added, "And he's even got red hair."

It was in that moment that Diana admitted something "closed off" inside of her, as she realized that he had rekindled his affair with Camilla Parker-Bowles.

The princess had endured a stressful nine months of pregnancy, as she was expected to produce a spare to her elder son, Prince William, and had even suffered a miscarriage before falling pregnant with Harry.

She had also suffered through a difficult 11 hours of labor - without any medication for the pain - to give birth to her son.

According to the princess, her husband's comment broke her heart, and it was essentially the beginning of the end of their marriage.

Prince Charles didn't stop his whining after his snide comment to Diana either. He later went and complained to her mother as well, further angering his wife.

At Harry's christening, Charles told her mother, Frances Roche, that he was "so disappointed" because he "thought it would be a girl." Roche snapped back at him: "You should be thankful that you had a child that was normal."

Diana explained that he shut down after that, because that is what he does when anyone answers back to him.

The most insulting part to Diana was the comment about the color of Harry's hair, as though there is something wrong with ginger hair. The trait is one that runs in Diana's family, with all of her sibling's boasting the bright hair color.

That trait also led plenty to wonder if perhaps Harry weren't the son of Diana's lover, James Hewitt, who also had red hair. Unfortunately for the rumor mill, that would be physically impossible, given that Diana only met Hewitt some years after Harry was born.

Charles insisted he had only been joking about his complaints, but the fact that he continued to do so seems to indicate otherwise.

When his son Prince William and daughter-in-law Catherine, Duchess of Cambridge, announced they were expecting a second child, Prince Charles reportedly hoped they would have a daughter the second time around.

He was delighted when Princess Charlotte was born.