Baby beside Me (2015)

Young Do-il plans for his wedding and to care for his baby. Although being a young father is not easy, he is happy. On furlough from the army, discovers that Ye-joon is not his biological son. His fiancée, Sun-yeong, disappears before he can ask her about it. He is a very young father, maybe too young, and desperately wants to find Sun-yeong.