
I am reading n I start thinking like how can someone forget if they had a lover in high school like seriously did something traumatic or what happen cause u just don't forget such details no matter ur age but I am still intrigued so I will keep reading it hopefully it can explain that part soon

I thought it was implied it had something to do with the mc having a traffic accident with his motorbike?
Didn't the diary say sth like "When he was released, he didn't remember"?
Unless it's a mistranslation, couldn't that mean "released from the hospital"?

Its the weakest point of the story for now but i think that there is some reason that we still dont know . Probably he had a accident or something or they lost contact after graduation and didnt met again while something bad happen to Sungho and he though that Dohyun was responsable

There is no amnesia that lets you forget only the face of ONE person. Even if they didn't met, you recognize a face decades later. That's something our brain is capable of. The only reasonable explanation would be that he has some kind of trauma, but I doubt it, because he slowly starts remembering him. It's more like he didn't care so much about the yellow eyed guy in the past. That's why he forgot about him.

I think he has something with his brain caze in chapter 23 he had a sound stuck in his head its obvious that he forgot something

And when he heard that sound in his head he was calling sungho true name i think so it has something to do with him

I actually feel that the story is very much probable. I also suffer from memory lost of nearly my whole childhood even up to my college and university days, and continually lose memories as time passes. Even if people bring it up I seem to have no recollection of it, I've also forgotten faces, if i see them today on the streets, it would be like meeting a stranger. When I was diagnosed as bipolar, I started noticing the gaps in my memory. I'm amazed that the uke can still slowly remember his past, I can't say the same for myself.

Memory loss is possible when you have a mental disease even though I'm pretty sure it's not that common. We have seen no signs of depression, a trauma, a personality disorder (none I know about) or some other disease. The main character is mentally strong. He acts pretty reasonable, is neither too scared nor fearless. We will see in the upcoming chapters. For me it just seems like the guy is potrayed as someone who doesn't care much about others. Of course I can be wrong.

Cognitive disorders do not have to occur with a personality disorder, psychological trauma or depression. Physical trauma to the brain can cause memory loss with no other apparent mental ailments. He was involved in a pretty bad accident so it's plausible.
When I saw the chapter update I was really looking forward to reading n then I saw he (╬ ̄皿 ̄)凸 so mad, like not cool man not cool at all, I feel sorry for the use to fall in love with such an ass