In March, Still’s partner Emma Saunders, a presenter on Sky Sports who previously worked for BBC Sport, said she was recovering from encephalitis, which is an infection of the brain.
“For multiple reasons, the main reason behind my decision is that I need to go back home,” admitted Still.
He would be a permanent replacement at Southampton for Ivan Juric, who left in April after the club were relegated from the Premier League with a record seven games left to play.
Born in Belgium to English parents, Still built his football career at Lierse and Beerschot before moving to France, where he became the youngest coach in Europe’s top five leagues when appointed by Reims, aged 30, in October 2022.
He joined Lens in June, 2024, on a three-year deal and led them to an eighth-placed finish in Ligue 1.
Lens have yet to confirm Still’s departure.
Sheffield Wednesday manager Danny Rohl was previously linked with the Saints job, but the compensation package to move to a club within the same division was thought to be too expensive.