Princess Diana’s heart was seemingly crushed when Prince Charles expressed disappointment over the gender of his second child.

When Prince Charles and Princess Diana officially divorced in 1996, there was much speculation about the real reason for the royal marriage’s breakdown.

The public always thought that the “third person” Camilla was the biggest “sinner”, but recently, a source close to the royal family revealed that the beginning of the rift in Diana and Charles’ married life was after a sentence from the prince in 1984.

Diana and Charles with their sons William and Harry at Highgrove House, Tetbury in 1989. Photo: UK Press.

Diana and Charles with their sons William and Harry at Highgrove House, Tetbury, 1989. Photo: UK Press .

In a 1991 interview, Princess Diana revealed that her relationship with Prince Charles “went downhill” after Harry was born, although during her second pregnancy, the couple became “very close”.

According to biographer Andrew Morton, Diana said the first thing her husband said when Harry was born was: “Oh my God, it’s a boy.” This statement devastated Diana, although Charles later insisted he was joking.

Before that, Diana knew the gender of her second child through an ultrasound but deliberately kept it a secret from her husband because she knew Charles would be disappointed because he always “wanted a daughter”.

Prince Charles and Princess Diana with their son made their first public appearance after the birth of Prince Harry in September 1984. Photo: UK Press.

Prince Charles and Princess Diana with their son in public for the first time after Prince Harry was born in September 1984. Photo: UK Press .

The late princess also revealed that Prince Charles had complained to the Queen at Harry’s christening and told Diana’s mother, Frances Shand Kydd, that he was “very disappointed – I thought it was going to be a girl”.

Firmly standing by her daughter, Diana’s mother later had a frank talk with Charles and said the prince should “realize how lucky he is to have a healthy, normal child”.

Princess Diana and her husband held Harry's christening in 1985.

Princess Diana and her husband held Harry’s christening at St. George’s Chapel, Windsor Castle, December 1984. Photo: PA .

British press reported in 2014 that Prince Charles hoped Prince William and Kate Middleton’s second child “would be a girl” after the couple had their first son George.

The harsh comment about his son’s sexuality was not the only hurtful comment Prince Charles made during his first marriage. He once said he did not like the fact that his youngest son had red hair – a colour that ran in Diana’s family.

For Diana, Harry was a miracle and a “complete joy”, helping her overcome the darkness, but the birth of her younger prince was also the moment that marked the collapse of her marriage.