Your little brother, Hwang Hyunjin who has a phobia of being forgotten which is called, athazagoraphobia.  You had a meeting and had to leave Hyunjin alone in the house.  Your guys parents went over seas for a honeymoon, so it was only you two.  But when you came back home, you heard

Father's eyes glued on the laptop. Mother always out,shopping with her friends. The two brothers only had each other to lean on. So when the unexpected thing happened,they couldn't help but to convince themselves that it was not their fault,even though the question kept replaying in their minds. Is it wrong if siblings fall in love with each other?