From what I understood, Dohu (black hair guy) got so depressed and distressed after they first broke up and Juheon (light hair guy) disappeared that he had health issues (maybe sleep and/or stomach issues)
They broke up because Juheon found out Dohu first got interested in him to use him as inspiration for a BL novel he was writing and started doubting their whole relationship thinking Dohu was just using him and felt nothing for him. Thus the realisation he did have feelings because he got so sad from the break up he got sick

i don't understand what's happening, i think i forgot the plot because of the angst
can someone explain to me what's happening pleaseee
why did black hair guy take medication?what does it have to do with the light hair guy ? why did they break up ?
other than im glad they could COMMUNICATE and hug