Furin Takuran Onsen: Sakaki Taeko-san no Hinichijou

Taeko's husband is caught in an affair, and she goes on a hot spring vacation to take her mind off her woes. When she meets a boy who's able to please her like her husband never could, one night just isn't enough, and a chance encounter develops into a long-lasting and passionate tryst...

(Source: Fakku!)

Note: A live-action AV adaptation (URE-062) was released on January 25th, 2021.