Kai and Krystal have been dating for 2 years now. Each and every day, Krystal has been seeming losing interest for Kai, even though he tries his best to impress her. One day, Kai meets Kyungsoo or how he calls him D.O. D.O secretly has a crush on Kai but gets heartbroken when Kai mentions his love for Krystal. D.O is a very caring friend who would always be there for Kai as for Krystal, the person who would break his heart the most. Finally, when Kai has realized his true feelings towards D.O, Krystal was only losing distances from him because he thought Kai was cheating on her after a misread text. Will Krystal be able to fight back for his lover or will he lose him towards D.O.