Serious cheating – We Fucked All Night To Forget Our Worries – Over 20,000 Sales On FANZA! Masterpiece Comic About Love And Lust That Was Immediately Made Into An Anime! Riho Fujimori (2021)

The protagonist Keita was cheated on by her 2-months girlfriend. Heartbroken meets at a bar with some university friends to comfort him. Particularly with Shuri, a lady who also has a boyfriend herself but she is not too happy about him. Thus, she makes a confident approach to Keita. There’s an animated version of this in Japanese (浮気と本気) if anyone is interested.