Watashi de Doutei Suteta Kuse ni

The post-breakup love comedy centers on childhood friends Kouta and Sakura who grew up together and were closer than best friends. Although they were rumored to be a perfect couple, Kouta and Sakura only dated once and did not harbor any romantic feelings for each other. After that one date, Kouta and Sakura continue their comfortable non-romantic relationship, but Sakura starts teasing Kouta about losing his virginity to her. Kouta, who prides himself in knowing everything about Sakura, gets quite a shock when he finds out that Sakura won a certain novel award. Gradually, Kouta starts to see Sakura as a girl pursuing her dreams, and their relationship begins to drift apart.
Source: ANN