Royal correspondent Robert Jobson has penned Charles at 70: Thoughts, Hopes and Dreams.
His book explores that the heir-to-the throne was pressured to marry the then-19-year-old by his father, Prince Philip.
The decision followed a report made by British tabloids falsely saying that the Prince of Wales had secretly brought the teenager onto the royal train for a nighttime tryst.
In the weeks leading up to their wedding in July 1981, “he would try to talk to her about his work commitments and what kind of day he’d just had — and Diana would stare back at him blankly,” Jobson writes in an excerpt published in the Daily Mail.
“I desperately wanted to get out of the wedding in 1981, when during the engagement I discovered just how awful the prospects were, having had no chance to get to know Diana beforehand,” Charles, 32 at the time, reportedly told friends years later.
Their 1981 royal wedding was watched by more than 750 million people across the globe.
The pair went on to welcome two children, Prince William and Prince Harry.
They divorced in 1996. Prince Charles has since remarried to Duchess Camilla.