Princess Diana Once Asked Photographer Anwar Hussein About Interfaith Marriage: 'She Wanted to Know About Islam'

Princess Diana had a complex relationship with the press, but she once sought advice on a personal matter from photographer Anwar Hussein.

Hussein — whose work chronicling Diana's journey from "Shy Di" in 1980 to the confident icon she became before her tragic death in 1997 at age 36 appears in Princess Diana Exhibition: Accredited Access, a "walk-through documentary" currently open in Chicago and Los Angeles, with New York City next — tells PEOPLE that Princess Diana approached him on a flight in the mid-1990s.

"All the lights were dimmed on the flight, and she came and whispered, 'Can I have a chat?' " he recalls in this week's issue. "She knew that I was married to an English girl, Caroline. She wanted to know about Islam. She was asking about being married when one person is Muslim and another is Protestant."

He continues, "She was interested because of what she was going through with [her then-boyfriend] Dr. Hasnat Khan. She didn't mention him, but she assumed I knew it. I think she was wondering how the family would react to him and things like that."

After splitting with her husband Prince Charles, Diana embarked on an intense romance with distinguished Pakistani surgeon and cardiologist Hasnat Khan. "She had wanted to marry him," royal biographer Judy Wade previously told PEOPLE. "She had this vision that together they could bridge east and west, crossing creeds and continents. They could save lives and make it a better world."

But Khan was bothered by the intense media scrutiny of their relationship. Their relationship fizzled and Diana went on to meet Dodi Al Fayed, who was with her the night she died in a car crash in Paris in 1997.

Over the years, Diana and photographer Anwar Hussein struck up a close working relationship, with the royal often talking to him at public events, during plane travel and at media receptions.

"The story of Diana unfolded in front of us," he says. "I saw every side of Diana. She was a genuine, good human being."

For more on the stories behind Hussein's iconic photos of Princess Diana, pick up a copy of PEOPLE, on newsstands Friday

Adds Cliff Skelliter, the exhibition's curator: "The personal relationship between a princess and a photographer who's with them all the time — they've got a closeness but also a distance in order to get a really interesting take."

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Although she confessed to feeling "awkward" when posing for photographers, she was also a masterful subject. "She had a canny way of showing her mood — whether she was happy or unhappy," says Hussein.

Also featured in the exhibit are photographs by Anwar's sons Samir and Zak, who have followed their father into royal photography by capturing the lives of Diana's sons Prince William and Prince Harry.

For information and to reserve tickets to Princess Diana Exhibition: Accredited Access, visit princessdianaexhibit.com. Use promo code PEOPLE15 to receive 15% off.