Scenes from a Marriage (but explicit), The Affair , or dark J-drama OVAs.
Here’s a concise review for Fuufu Koukan: Modorenai Yoru Season 2 (also known as Couple Swap: A Night of No Return ), written for an adult audience familiar with the genre. Rating: ★★★★☆ (4/5) fuufu koukan: modorenai yoru season 2