When Prince Charles and Princess Diana married on July 29, 1981, 750 million viewers from around the world tuned in to watch the duo officially become husband and wife. In addition to the vow exchange, fans of the royal family—or simply of the couple themselves—took in the bride’s trend-forward gown, the Victorian-inspired bridesmaids dresses, and, of course, the balcony kiss. However, prior to the big day and all of the excitement surrounding it, Charles made sure to give his soon-to-be wife some private words of love and encouragement.

In The Duchess: The Untold Story, author Penny Junor detailed how Charles sent Diana a letter and gift on the eve of their nuptials. “The night before the wedding, which Diana spent at Clarence House with her sister, Jane, he sent her a note, along with a signet ring bearing the Princes of Wales feathers,” Junor wrote in the book. She added that in the note, the prince tried to give a boost of confidence to his bride: “I’m so proud of you, and when you come up, I’ll be there at the altar for you tomorrow. Just look ‘em in the eye and knock ‘em dead.” The move may not have been entirely unusual for the pair, as the princess was known to send romantic cards to Charles, according to her former butler, Paul Burrell. Yet Diana’s letters often went unreciprocated, which made the prince’s decision to give such a message to Diana a bit surprising. “It’s such a sad thing to say that he never loved her, and so he never returned the compliment,” Burrell told Marie Claire. “He wasn’t romantic. He tried to be, but he didn’t have a romantic bone in his body.” 

Some say that the red flags in the relationship were noticeable even at the couple’s royal wedding. Judi James, a body-language expert, told The Sun that Diana looked visibly uncomfortable on the day of the duo’s nuptials. To James, the princess appeared shy, hesitant, and anxious. These emotions seemed to continue over the course of the celebration; as the newlyweds sat in the carriage together, Diana looked troubled at certain points, according to James, and attempted to seek her new husband’s attention to no avail. Such an analysis indicates that the prince’s attempt at a romantic gesture prior to saying “I do” did little to ease Diana’s fears and nerves about the marriage. 

The tension between the two only continued over the course of their marriage. In 1986, five years after the pair tied the knot, Charles began his affair with Camilla Parker Bowles, and the married duo started to live separately from one another. And on December 10, 1992, the prince and princess officially announced their separation. “This decision has been reached amicably and they will both continue to participate fully in the upbringing of their children,” Prime Minister John Major said in an address at the time. The pair finalized their divorce on August 29, 1996, ultimately going their separate ways after 15 years of marriage.