Alt. title: 苦いのテーマ | The Theme of Bitter
From Lewd4Yaoi Scans:
Two guys who are stupid in love are drastically changed by one man. An irresistible love triangle!
Arata & Natsuki have been dating since they were in Junior High. However, at the Outdoors Club at the university Natsuki attends, he meets a senior who is kind and gentle. While being attracted instinctively, he…
– chapter 4