Princess Diana, unfortunately, knew that everything she had with Prince Charles already ended before they even had a fresh start.

Over two decades after Princess Diana died in a tragic accident, the saddest royal wedding ever still creeps into people's minds. Although the event was regarded as the wedding of the century, something happened there that made the royal princess uneasy.

A royal expert recalled this week that none of the 750 million people who tuned in to the wedding noticed Princess Diana's uneasiness. What thought to be a perfect fairytale was actually chaos from the start - and Prince Charles' "other woman" made things complicated.

In an episode of "Channel 5 documentary Charles and Camilla: King and Queen in Waiting" (via Express), former BBC correspondent Jennie Bond revealed that Princess Diana was not happy during her wedding day.

According to the royal expert, the Princess of Wales told her she felt like "a lamb to the slaughter" as she walked up the aisle.

The supposed happy day for the late princess became a tragic one soon after she realized that some things were not right.

Princess Diana Heartbreak: What Caused Her To Feel Uneasy

Bond detailed the real reason why the late princess felt uncomfortable on what should have been a special day. Per the royal expert, Princess Diana saw Camilla - the woman who would cause her divorce from Prince Charles.

The recordings of the princess' stories were handed to Andrew Morton. In return, the journalist published the book "Diana: Her True Story" and disclosed the unhappiness surrounding the marriage.

Years after their marriage, the Prince and Princess of Wales gave birth to Prince William and Prince Harry.

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However, after welcoming their second son, Princess Diana revealed that it marked the beginning when her relationship with Prince Charles started to be on the rocks. Two years after Harry was born, Prince Charles reportedly restarted his romantic entanglement with Camilla Parker-Bowles.

The 2013 documentary "Royalty Close Up: The Photography of Kent Gavin" which was aired on Amazon Prime, shared the same story of heartbreak, revealing how she felt when she found out about the infidelity issue.

"She said to me after all the rumors of the marriage and everything, she said on a flight somewhere: 'Kent, you won't believe it, but I still love him," Gavin recalled.

In the end, they decided to separate in 1992 before officially filing for divorce in 1996.

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