Responses
All the focus is on how devastated he was cause of Hakyung's "dead". But, we have to remember that he ALSO lost his grandpa. Imagine waking up from an accident and learn that not only your grandfather (who you were very close with) but also the person you love are both dead.
I really didn't expect this plot twist of there being two car accidents. I was confused on why he said he lost his memories on an accident but then when we saw him recover he seemed to still clearly remember a lot of things. He lost his memories from his suicide attempt (second "accident") when he drove his car off the rails, which is why he didn't immediately recognize Ha kyung. He truly was in love with him and was so devastated when he was told that Hakyung died. Probably survival guilt as well...