Watch My Sister's Friend 3 (2019) Official Trailer

Sorry! It was because he was lonely...

Min-wook has a crush on his roommate, Young-su's sister, Soo-jin. However, she plans to marry a man who meets the conditions for Su-jin soon. She hides her heart and wishes her sister happiness, but when she sees her divorced a few months later, her old feelings come back to life. Her divorced Su-jin stays with her brother's house for the time being, and Min-wook and Su-jin, who have been living in her house for the time being, are now trying to confirm their love for each other...?