When Lady Diana Spencer married into the royal family in July 1981 (the same month she turned 20 years old), she immediately became the star of the show. Her beauty, her style, her shyness, her warmth, her humor, her presence captivated the globe—quickly making the Princess of Wales the most famous woman in the world. And, unfortunately, it was a point of contention between Diana and her husband, Prince Charles, who hated Diana stealing the limelight from him.

But Diana “wasn’t aware of the royal machine” before she married Charles (who is, of course, now King Charles), The Mirror reports. Diana was only a tender 19 years old when she became engaged to Charles in February 1981 and had no idea what she was getting herself into and agreeing to, a friend of hers said. “The pair wed in a lavish ceremony at St. Paul’s Cathedral in 1981—and whilst it seemed publicly like a fairytale romance, behind closed doors Diana struggled,” The Mirror writes. “The couple’s marriage eventually broke down acrimoniously, with many of their issues playing out on the front pages of the newspaper.”

One of the foremost sources of tension was Diana’s massive popularity, The Mirror reports, adding that “In the early days of their union, Charles would often be overshadowed by his beautiful wife, with crowds cheering for the princess and screaming her name, desperate to get a glimpse or a short conversation with her instead of the future king.” 

During her controversial Panorama interview on the BBC in 1995, Diana herself confirmed as much, saying “The pressure on us both as a couple with the media was phenomenal, and misunderstood by a great many people. We’d be going ‘round Australia, for instance, and all you could hear was, ‘Oh, she’s on the other side.’ Now, if you’re a man like my husband—a proud man—you mind about that if you hear it every day for four weeks. And you feel low about it instead of feeling happy and sharing it.” (Charles and Diana undertook a tour of Australia and New Zealand together in March and April 1983, bringing along baby Prince William with them, who was just nine months old.) Claiming the attention pointed at her caused “a lot of jealousy,” Diana added “A great deal of complicated situations arose because of that.”

Diana’s friend James Colthurst—who knew Diana from her teenage years until her death in 1997—claimed that not only did Diana not know what she was doing when it came to the royal machinery that works to keep the institution of the monarchy going, but that the Firm didn’t know what to do with her star quality, either. (Colthurst, for context, is perhaps best known as acting as the go-between when Diana secretly collaborated with journalist Andrew Morton on his bombshell 1992 book Diana: Her True Story. “A mutual friend of both parties, Colthurst conducted interviews on Morton’s behalf, recording hours’ worth of tapes of Diana answering the author’s questions that would eventually become the book,” The Mirror reports.)

“Her engagement and marriage to Prince Charles brought her global fame,” Colthurst said, per The Telegraph. “But I felt, when she joined the royal family, she may not have been fully aware of the machine she was in. The Firm, for its part, was unaccustomed to having a superstar in its midst, and I don’t think it knew how to cope with the enormous amount of publicity she generated.” 

Colthurst added that “She wasn’t given much of a brief at Clarence House in the buildup to the wedding, and no one realized quite what was about to happen: that she would take off and become immensely popular in her own right,” he said. “She didn’t have a big support team at the Palace herself. She was just trying to do her best. When she did what she thought was right, it was well-received by the public, but not always by the Firm.”

After 11 years of marriage and two children, Charles and Diana separated in 1992 and ultimately divorced on August 28, 1996, just one year and three days before her death in a Parisian car accident that next August 31.