Dongjeongui Hyeongtae

One wedding, two heartbreaks.
Yu-Ri attends the wedding of his unrequited love. There, he runs into his former homeroom teacher Seon-Woo, who seems just as heartbroken by the union. But little does he know that Seon-Woo's tears are meant not for the bride, but for the groom...
(Source: Manta)
Note: Includes 38 side story chapters and 17 epilogue chapters.