Isogaba Sefure.

Sasada is getting married?! Hibana has been in love with her coworker forever, so imagine her disappointment when she finds out about his engagement! Hibana's got to forget about her broken heart, so she enthusiastically attends her high school class reunion. There, she reunites with Kyota. Kyota was Hibana's best guy friend. They find kindred spirits in each other once again, bemoaning their bad luck in love -- and decide to become friends with benefits?! Sure, they're not kids anymore, but will the two of them really be able to keep their relationship purely physical...? (Source: Manga Plaza) Note: Includes five additional 0.5 chapters