PLEASE EXPLAIN
idk about this part but i assume he got hurt after being attacked when the apocalypse started, his father gave him first aid and when he started getting dehydrated so his father went out to get water, and as you can see when he comes back to give mc water, ml kills him (probably because he didnt see him as useful). i think the trauma from his head, and the death of his father (right in front of him) caused him to lose his memories.idk if yall are curious about the guwon part but ill explain it anyways, he lied as to keep his fathers death a secret, and wanted him to see his fathers body himself as a surprise for him to be happy, but obviously he loved his father so its 100% safe to say he was NOT happy. on the ride back he gains his memories back and throws up due to disgust (cause he liked guwon and had sex with him).
anyways i think thats all there is to explain, i hope you all understand now. (sorry for long paragraph)
i don't get how everyones confused, i personally think the story's easy to follow and makes sense, of course i would love to explain but im horrible at explaining things ;;