Taboo: Forbidden Love (2015)

Eun-ji is a idol trainee who gets abandoned by Jin-tae her sponsor, so she heads back down to her sister Sun-yeong's home. Her first love Joon-hwan is now her brother-in-law so he welcomes her but Sun-yeong treats her like a child and worries that Eun-ji might go down the same path she did when she gave up becoming an idol. Eun-ji and Sun-yeong quarrel often and Joon-hwan comforts Eun-ji every time. Eun-ji starts to depend on him and he also secretly tells her why he quit his job. One day, Sun-yeong goes on a business trip for a week but before she leaves she tells Eun-ji how sorry she is. They share a momemtum with two wooden dolls. All alone by the two of them at home, Eun-ji tries to embrace Joon-hwan's heart by showing him a scrap note she made of his articles. He is grateful for Eun-ji and starts to open up to her. The two of them cross a line that shoud never be crossed and as time goes, they fall deeper and deeper into each other.