Let me guess.. We'll get a sequel where kouchi becomes the uke and then they will cross paths again in another manga. Sounds familiar? Anyone?
http://www.mangago.zone/read-manga/sabita_yoru_demo_koi_wa_sasayaku/
That's the manga that they're talking about. And this one it's the sequel:
http://www.mangago.zone/read-manga/hadakeru_kaibutsu/
In the summary of the second link they explain the order you can read the story about this characters. Tbh, I have to read the sequel too, because I only read Sabita, and I still hate Kan-chan for what he did to Yumi. But enjoy!
I'm guessing Dohyun doesn't remember Sungho because of psychological repression. Sungho affected and hurt him so much in the the past that his mind decided to forget that's why he ended up with represssed memories. MAYBE
Someone asked and the author said it's because Dohyun's life is harsh and exhausting with nothing in his life that's dependable so because of stress he doesn't remember Sungho.
Here's the link for full Q&A chapter, it's in Chinese though:
https://m.dm5.com/m544423/
At least Subin knows he's being a dick. and damn, that red hair friend is sooo levelheaded.
P.S
I want him to be gay and idk, maybe end up with Hyung. Hahahahahahahaha kbye.
That wouldn't be too bad, if hyung ended up with shit Jun coz he seems dependable.
However, I will still be rooting for hyung and subin. (=・ω・=)