Prince Charles, Princess Diana
Prince Charles and Princess Diana got engaged 37 years ago. Pictured: Prince Charles, Princess Diana arrive for a British Film Institute dinner at 11 Downing Street, the official residence of the Chancellor of the Exchequer, Feb. 2, 1982. Central Press/Hulton Archive/Getty Images

Prince Charles and Princess Diana would be celebrating their 37th engagement anniversary if only they were still together and if the princess was still alive.

To mark the special occasion, some of the sweetest photos of the royal couple were released online. One of the photos shows a young Prince Charles sitting on a plane, while Princess Diana is looking at him and smiling from ear to ear.

In the second photo, Prince Charles and Princess Diana are lying on the bed and cuddling with Prince William. A third picture was taken on June 22, 1982 on their way to leave St. Mary’s Hospital after Princess Diana gave birth to Prince William.

Princess Diana was also photographed sitting in between Queen Elizabeth II and Queen Mother, while carrying Prince William in her arms. Princes Charles and Philip were standing behind the three women.

Another photo of the ex-couple shows them standing outside The Lindo Wing at St. Mary’s Hospital after giving birth to Prince Harry.

But despite their happy faces in the pictures, Princess Diana revealed that her marriage to Prince Charles was a tumultuous one. Both of them cheated on each other, and they finally divorced on Aug. 28, 1997. A year and three days later, Princess Diana died in a car crash in Paris.

During a previous interview (via The Telegraph), Princess Diana said that she had only spent time with Prince Charles 13 times before they got married. “He’d ring me up every day for a week and then he wouldn’t speak to me for three weeks. Very odd. And the thrill when he used to ring up was so immense and intense.

Princess Diana also called her wedding day to Prince Charles the worst day of her life. “If I could write my own script I would have my husband go away with his woman and never come back,” she said. Princess Diana was referring to Prince Charles’ then-other woman, Camilla Parker-Bowles. He and Parker-Bowles are now married.