beta
Seeing the raws, I re-read the manga assuming that he remembered all along and some of the things he says in the present make a lot more sense. When he muses to himself, and when he talks about Jiyoung infront of Hakyung to get a ruse out of him and to watch his reaction. Why would he lie about forgetting that summer, I don't particularly know, but from the raws, he definitely doesn't trust his family and likely pretended to forget so they don't worry about him while he continues to look for Hakyung.