Everybody knows what happened to Princess Diana and Prince Charles' love story. This resulted in the assumptions that the Prince of Wales regretted the time that he proposed to the late People's Princess. But, in an unearthed biography, it was revealed that the future king sent a loving letter to her then-future wife before their wedding.

Before Prince Charles and Princess Diana got engaged in 1981, they, reportedly, saw each other for only a dozen times. Although they seemed to be a mismatched couple, they said to be perfect for each other, as the Princess of Wales also came from aristocratic circles.

According to 9Honey, the proposal marked a dramatic shift to the late princess' life. At the time, she was still working as a kindergarten teacher and sharing a London flat with her friends. However, everything started to change when they became engaged.

The future king proposed a few days before she went to Australia so that she could think about it when she was away. She never took the time she needed and gladly said yes right then and there.

Princess Diana moved out of her flat, which Prince Charles never visited, and told her students she would miss them. Anyhow, after the announcement of their engagement, their relationship started to disentangle.

Express noted that Princes William and Harry's mom began to find it hard to live life as a senior royal. Some even believed that the Duke of Cornwall started to question himself as to why he proposed.

But despite the doubts, Howard Hodgson revealed in his 2007 book, Charles: The Man who will be King, Camilla Parker-Bowles' husband was supportive of his former wife. He even sent her a note before their wedding, saying he was proud of her and he would be there for her when she arrived at the altar.

He even advised her to look people in the eye and knock them dead. Along with the letter was a signet ring, which Princess Diana donned on their wedding day. However, there were rumors that Prince Charles slept with Camilla in the week that their marriage would take place.

Was he already unfaithful even before they tied the knot? Queen Elizabeth, reportedly, held a dinner for Princess Diana and friends two nights before the big day. A huge reception then followed it.

Camilla and her then-husband, Andrew Parker-Bowles, attended the event, but they both left together later. However, Princess Diana seemed to believe that Prince Charles slept with his now-wife at the time, making imaginary pictures in her mind that made her convinced that it was true.