Prince Harry’s latest tour to Angola is keeping Princess Diana’s memory alive by continuing some of the late royal’s most important humanitarian work—but his wife, Meghan Markle, won’t be joining him on the meaningful trip. While the couple ended a period of solo appearances earlier this year, packing on the PDA at a surprise joint Invictus Games appearance in Vancouver, the lifestyle entrepreneur was notably absent as Prince Harry kicked off his latest trip—and the reported reason is so sad.

Prince Harry made an unexpected solo visit to Angola on Tuesday, July 15 as part of his work raising awareness for the country’s ongoing war recovery with The Halo Trust. During his trip, the royal will follow in his late mom’s footsteps (literally) by recreating the walk that Princess Diana took across an Angola minefield in 1997, just months before she died in a car crash that August, according to People. Prince Harry also took this walk in 2019, and last September, he called continuing his mom’s work in the region a “responsibility that I take incredibly seriously.”

While fans were surprised that Markle wasn’t by his side as he landed in the African country, a source told the Daily Mail that ongoing security concerns were the reason that Prince Harry decided to visit Angola by himself. “The Duke won’t let his wife go to England over security concerns, so there was no chance he’d allow her to go to Angola to walk across landmines,” the source shared. However, the insider noted that Prince Harry hopes that his visit would still raise funds to help with war recovery efforts in the country.

Prince Harry’s concerns about security for his family are nothing new, as the royal recently lost a years-long legal case to retain taxpayer-funded security for the Sussexes. However, while his kids and wife might not be able to go with him to Angola, Prince Harry previously told The Telegraph that his son Prince Archie has started developing an interest in his work there, and even asked to see footage of Princess Diana’s iconic walk.

“Archie was asking about landmines, so I was talking about how some of these guys were blown up,” Harry told the publication, revealing that the difficult conversation became a chance to talk about his grandmother.

“Interestingly, it gave me a chance to talk about my mum, his grandma, which I didn’t even really consider, so that became the outcome of the story for him,” he added, revealing that Archie “wanted to see videos and photographs of his Grandma Diana out doing her thing for landmines all those years ago. It produced a very interesting conversation between me and him, different to what I thought it would be.”