Princess Diana was instantly smitten when she met George Michael for the first time.

In 1985, the Princess of Wales attended the Live Aid concert in London’s Wembley Stadium. The Wham! singer, along with Queen, Elton John, David Bowie and others, performed for the televised event to raise money to fight famine in Ethiopia. By then, Diana had already been a fan of Michael, but after personally meeting him, her feelings for the closeted idol were clear.

"Princess Diana had a thing for pop stars," James Gavin told Fox News Digital. "She was a fan girl. She was infatuated with pop stars and she got to know many of them. She worked with some of them and invited them to perform at her events… Elton John and Princess Diana had a bond, but George Michael was shy about that. And as for George, there was no denying that she developed a crush on him."

Princess Diana

Princess Diana watches from the crowd during the Live Aid concert at Wembley Stadium in London on July 13, 1985. The concert raised funds for famine relief in Ethiopia.  (Georges De Keerle/Getty Images)

Gavin has recently written a book on the late singer titled "George Michael: A Life." It came out more than five years after Michael was found dead on Christmas Day 2016 at age 53. It takes an in-depth look at Michael’s early years, his rise to stardom, and the tragedies that followed him. Gavin said he spoke with about 250 people who, after some hesitation, were willing to share their memories of the pop star.

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In the book, Gavin also explored Diana’s connection with Michael, which lasted for 12 years.

"George Michael was shy about Princess Diana for two reasons," Gavin explained. "One, she was the Princess of Wales. Even though George Michael was George Michael, Princess Diana was more popular than the queen. And he didn’t want to seem as though he was stalking Princess Diana… George became aware of the fact that she had the hots for him. Now, of course, this wouldn’t have gone anywhere, but you can imagine how uncomfortable this made him. So he kept her at a distance. The friendship consisted of occasional lunches and phone calls."

Princess Diana George Michael

Princess Diana chatting with George Michael at Wembley Arena in London, for the Concert of Hope, a benefit concert on World AIDS Day, on Dec. 2, 1993. (Princess Diana Archive/Getty Images)

Gavin pointed out how Diana was quoted as saying she found Michael "very gorgeous." Michael issued a public response that read, "Thank you, ma’am – you’re pretty smashing yourself." But the royal, whose marriage to Prince Charles was struggling behind palace doors, saw a friend in Michael who was close to her in age.

George Michael A Life Book

James Gavin has written a biography of the pop star titled "George Michael: A Life." (Harry N. Abrams)

"When it came to Princess Diana, George also found a kindred spirit, someone like him who was a public figure and trapped in this gilded cage," Gavin explained. "And I think it was impossible not to be shy around her. She was the biggest star in England, far beyond greater than any of the pop stars she loved. Diana was a sweet girl. She was no dummy, but she was very much an English rose. Unfortunately, she could never have a normal relationship or friendship in her life. But there would always be some distance between George and Diana. He didn’t want to exploit her in any way. And he was also uncomfortable."

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Still, Gavin said the pair supported each other during tough times.

George Michael

Author James Gavin detailed in his new book how Princess Diana was smitten with George Michael. (Michael Putland/Getty Images)

In 1996, Diana called Michael late at night. At the time, she was facing a public divorce from Charles. Michael, who was with his friend Andros Georgiou, heard the familiar voice as she was recording a message for him. Michael immediately picked up and the pair shared a heartfelt conversation despite the tape still rolling. That recording later wound up in the possession of Georgiou, who eventually sold it.

"The answering machine recorded the first three minutes of the conversation," said Gavin. "Now imagine the Princess of Wales calling you late at night while you were watching television with a family friend. You could hear the affection as they spoke to each other. Diana is almost giggly and shy. George was flattered. But neither of them could let their hair down with each other."

"There would always be a distance between Diana and Michael," Gavin continued. "It would be very hard for her to find real friends who didn’t want something from her. George Michael experienced something similar, as most superstars endure. You want to have people in your corner who will love you for you and not for who you are. These were two people suffering from the same social affliction… And George himself said that he was uneasy about the fact that he felt she had the hots for him."

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Princess Diana tapes

A case of cassette tapes that belonged to Princess Diana, containing albums by singers Diana Ross, Elton John and George Michael, is pictured at Buckingham Palace in London on July 20, 2017. (Tolga Akmen/AFP via Getty Images)

After Michael’s mother passed away in 1997 from cancer, it was Diana who personally called the devastated star and consoled him. During their friendship, Michael would lovingly refer to Diana as "my darling." At one point, he even gave her a gold watch. But Michael, who was secretly gay, remained in the closet during Diana’s lifetime.

Later that year, Michael faced another sudden loss. On Aug. 31, Diana died from injuries she sustained in a Paris car crash. She was 36 and the royal, along with her chauffeur, bodyguard and new boyfriend Emad "Dodi" Fayed, were being chased by paparazzi. Diana’s bodyguard was the sole survivor.

"He was heartbroken," said Gavin. "George knew what it was like to be relentlessly hounded by the press… The poignancy of her passing at such a young age really did rock his world. He was also deeply affected by Whitney Houston’s death [in 2012]. He was petrified that he might end up the same way that Whitney did. And in fact, that pretty much happened."

George Michael Princess Diana funeral

Pop stars George Michael and Elton John leave Westminster Abbey after the funeral service of Diana, Princess of Wales. (Johnny Eggitt/AFP via Getty Images)

Throughout his career, Michael’s drug use and taste for risky sex brought him into frequent brushes with the law, most famously in 1998 when he was arrested for public lewdness in Los Angeles. He managed to turn the incident into fodder for a song that poked fun at his behavior, and his acknowledgment of his homosexuality at that time made him even more popular.

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But Michael’s struggles with drugs were no laughing matter. His addiction was well chronicled by the press as Michael tried to numb himself from the anguish he endured privately.

"Back in the Wham! days, he experimented with cocaine, but he didn’t really like it," said Gavin. "In the early ‘90s, George got into ecstasy. But then Anselmo Feleppa, who was no doubt the love of his life and his soulmate, died in 1993 of AIDS. He was racked with pain. He turned to pot and became a full-time stoner. His album ‘Older' was made completely under the influence of pot. Then around 2003, 2004, he got into a party drug called GHB. In my opinion, more than anything, that’s the drug that did him in. But he didn’t stop there. He got into crack cocaine and was arrested for possession of that."

George Michael arrest

Like Princess Diana, George Michael felt he was trapped in a gilded cage, James Gavin shared. (Getty Images)

Gavin said Michael was attempting to escape the losses of Feleppa and his mother, "the one person who offered him unconditional love and acceptance and wanted nothing more then for him to be happy."

"The two most precious things in his life were robbed from him," said Gavin. "He really began spiraling out of control. He spent the rest of his life mourning them."

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According to Gavin, Michael became "highly reclusive" in his final years.

George Michael book

George Michael arrives for sentencing on driving under the influence charges. (John Phillips/UK Press via Getty Images)

"His inner circle shrunk, but his self-destruction did not," Gavin explained. "His sexual appetite did not diminish nor did his physical appetite… This was a guy who was obsessively image-conscious in his early years… It became painful for him to look in the mirror. His creative output thinned out dramatically. He was finding it difficult to write songs. And his voice invariably diminished because of all the smoke he was ingesting… He was in a very dark place. He felt like the world was closing in on him."

Michael died of natural causes as a result of heart disease and a fatty liver, a British coroner would later reveal.

George Michael death

Flowers, photographs and candles are placed in tribute outside the home of George Michael on Dec. 28, 2016, in London, England. The pop star died on Christmas Day at the age of 53. (Jack Taylor/Getty Images)

"I hope the reader empathizes with George’s struggle," said Gavin. "… It’s hard for people to feel sympathy toward a star with such wealth and acclaim. And yet, what drove George to achieve all of this success was his brokenness inside. He had the talent to get him there. He was a big-hearted, generous, beautifully well-mannered terrific guy. But he was also a wounded kid inside… Despite all the pain he endured, his music made such a difference in people’s lives. It made them feel good. It made them happy. His name still brings people joy. There’s just something about him that still touches people’s hearts."

The Associated Press contributed to this report.