okay so ever since Doyoung saw his partner Taewoo die in front of him (the car incident) he's convinced that if he will erase every memory of the things/persons he loves then he would be able to stop the tears and be happy 'tomorrow'. meanwhile Juhyeok (the boss) loves Doyoung, but since Doyoung can remember him after all this time, he's heartbroken because that means that Doyoung has no interest in Juhyeok, that's why Juhyeok tells Doyoung "why do you think that you can never remember Kangwoong?" (basically that means that Doyoung is interested in Kangwoong, and that's the reason why Juhyeok always tell Kangwoong to leave Doyoung alone and to mind his own business) in the end Doyoung finally remembers Kangwoong, so that means that he's finally facing his past in order to have a peaceful and happy future
Like That Winter Flower