Anata no Kiss de Kaki Kaete

Yukina has had an unrequited love for her first love for 15 years. However, her love remains unrequited, and she ends up attending her first love's wedding. There, she meets novelist Shun, who gives a speech on behalf of his friends with a sad look in his eyes. In fact, the two have an unexpected thing in common...?! The two have a combined total of 35 years of unrequited love. A heartbroken office lady and a heartbroken novelist share a mutual love story! (Source: Kodansha, translated)