Hitozuma Onsen Okami Saitou Shizuka ~Otto no Mae de Bakunyuu Ryoujoku Houshi

Main character is an adopted son at the family owing a hot spring inn. But management has deteriorated, so rich nobility customer suggests selling lady owner's body to prosperous customers starting with him. Husband can do nothing but watch his wife humiliated in front of him.

[From vndbreview]