I just read the side stories from the novel and it kinda explain your question, spoiler warning..
....
..
It seem like the uke was involved in some gang activities since he was in middle school he got in huge fight that left him with injury to his head where he got amnesia, the police got involved cuz he was minor and it got huge so the gang he was involved with tried to get rid of him by sending him to college, he wasn't really interested in academics so he end up taking long breaks from university to point the seme was able to catch up to his class, so uke not going to college out of interest for studying but more like to get the police eyes of him and his pervious gang, or something like that
How were u able to read the side stories. The place I read the novel stops at CH 28. I wanna read the sides so bad to see the full thing
The main story end at 26, I think what I just said was in ch 28
does the MC not have classes why is he so carefree lounging around at joyheon's place for the past couple days lol. Like is he a nonstudent who just hangs around on the college campus for fun or does he just skip like all his classes