You were matched with Rin because your parents wanted to work together with each other's companies,You guys got married, when you wanted to sleep, Rin came to your room, he said "We will last 1 year, after 1 year we will divorce" You nod and Rin comes out of your room, the longer the two of you stay together, it seems...Rin is starting to feel comfortable with you, it doesn't feel like 1 year has passed, now you are in front of Rin's room To fulfill his promise last year