The Song and Shen families have been close for generations. From childhood on, Shen Du was better than Song Zhiyi at everything. In their final year of high school, Song Zhiyi's mother even took it upon herself to have her move into the Shen family home. Song Zhiyi vowed to compete with him until graduation. But living under the same roof, Shen Du would warm milk for her late at night and be the first to rush to her defense when someone picked on her. Song Zhiyi realized her dislike for him was starting to change into something else. Just when she thought Shen Du might like her too, the school beauty linked arms with him in front of everyone, and he smiled without pulling away. It was the first time Song Zhiyi tasted heartbreak. She moved out of the Shen home and buried herself in her studies, swearing that after the college entrance exams she would never have anything to do with him again. But Shen Du acted as if nothing had happened and waited for her outside the classroom every night. On the eve of graduation, Song Zhiyi found a yellowed photograph in Shen Du's desk. On the back was a line of writing, and the truth made her cry herself hoarse in the dead of night. Pride kept Song Zhiyi from admitting how she felt for three years, but in the end she understood: the first to lower their head hasn't necessarily lost. They may simply have learned to love sooner.
I don't understand, why did the male protagonist suddenly disappear...?