Prince William
Prince William, photographed while giving a speech at the Diana Awards in London, on May 18, 2017, opens up about the things he wishes Princess Diana was around for. Getty Images

It’s been nearly 20 years since Princess Diana’s tragic and unexpected death. In the years since, eldest son Prince William has gone on to marry and start a family — an experience he admits isn’t the same without his mother.

In an interview with British GQ, the 34-year-old royal said he wished Princess Diana could have been around to meet Kate Middleton and their two children, Prince George, 3, and Princess Charlotte, 2. He revealed that he’s still “sad” that they’ll never have the chance to truly know her. Additionally, Prince William said he misses his mother’s guidance.

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“I would like to have had her advice,” he said. “I would love her to have met Catherine [Duchess of Cambridge] and to have seen the children grow up. It makes me sad that she won’t, that they will never know her.”

Though he still has these thoughts, William told GQ he’s come a long way since his mother’s death in 1997. Mourning was difficult for he and his family, being in the public eye, but they managed. Now, after two decades, Prince William says he’s “in a better place about it.”

“It has taken me almost 20 years to get to that stage,” he said. “I still find it difficult now because at the time it was so raw. And also it is not like most people’s grief, because everyone else knows about it, everyone knows the story, everyone knows her.”

Prince William will delve deeper into his feelings about his mother’s death — both at the time and all these years later — in a documentary set to release closer to the anniversary. The film is being produced by HBO and will be told by Prince William and Prince Harry. Nick Kent, who serves as the documentary’s executive producer, teased the unique project in an official statement.

“The film will show Princess Diana in a way she has never been seen before, through the eyes of the two people who knew her best,” he said.

The documentary will feature other testimonials from individuals close to the Princess who “have never spoken publicly before.” It’ll cover a variety of topics as well. Among the things expected to be shown are her humanitarian efforts, which covered a fight to end homelessness, HIV, AIDS and more.

Prince William’s been talking about his mother’s passing more and more in recent months. He’s done so in conjunction with he and Princess Kate’s efforts to raise mental health awareness. A spokesperson for the eldest royal son of Princess Diana claims he’s been outspoken about the issue because he feels that mental health is the root of many other societal problems.

“Through their work with young people, emergency response, homeless charities, and with veterans, Their Royal Highnesses have seen time and time again that unresolved mental health problems lie at the heart of some of our greatest social challenges,” the spokesman said.

Prince William and Princess Kate aren’t the only members of the royal family who’ve been outspoken advocates of mental health. Prince Harry opened up about seeking help to deal with the grief of losing his mother during an appearance on Bryony Gordon’s Mad World podcast. He admitted that bottling up his emotions lead to years of “total chaos,” which coupled with encouragement from his older brother pushed him into treatment.

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“I can safely say that losing my mum at the age of 12, and therefore shutting down all of my emotions for the last 20 years, has had a quite serious effect on not only my personal life but my work as well,” he said (via the Telegraph).

The 20-year anniversary of Princess Diana’s death will be August 31, 2017. Princes William and Harry have commissioned a statue of her at Kensington Palace according to the New York Times.