The 35-year-old is said to be spending the weekend in Capri to attend a charity ball as he is a brand ambassador for George Clooney's Casamigos tequila which sponsored the high profile invite-only Unicef Summer Gala, the Daily Mail reported.
On Friday, July 30, Brooksbank was photographed on a boat before the big event where he was seen exploring caves around the coast with former Glamour magazine editor Rachel Zalis, who is now Casamigos's global director, and Maria Buccellati, a model turned fashion ambassador.
The group was also joined by model Erica Pelosini. Brooksbank was reportedly seen guiding her around the boat with an arm on her back. The model had a towel around her but removed it to go topless.
Brooksbank was also sighted returning to the deck several times to check his phone, perhaps to contact Eugenie.
Pelosini and Buccellati are said to be pals with Israeli socialite Hofit Golan, who is friends with Prince Andrew's ex-girlfriend Lady Victoria Hervey.
A source told the Daily Mail that Eugenie did not join her husband because he was "there to work at the ball," as he was reportedly given the job of keeping an eye on the cocktail bar for A-listers such as Katy Perry, John Legend and Heidi Klum, as a cocktail hour was scheduled in as part of the night.
Steve McQueen's 1961 Cooper Formula Junior race car and an Andy Warhol art piece were said to be some of the things auctioned off to raise funds for Unicef programmes, with the ticket price ranging from $11,124 (£8,000) to $34,762 (£25,000,) the Daily Mail noted.
Eugenie and Brooksbank met in 2010 while skiing in Switzerland, and he earned the nickname "barman Jack" because he was working at a restaurant and wine bar in Central London at the time. The royal couple tied the knot in 2018 and welcomed August in February.