I was re-reading the earlier chapters, and I think the MC is misremembering his father being killed by Guwon due some kind of trauma.
Like, with his strange panic attacks, him waking up attacking guwon, guwon (who clearly isnt completely human) having an affinity with him…. I think mc also isnt completely human, and so his dad tried to kill him with the whole “my son is a monster” reasoning, and MC was actually the one to kill his father in self defense or smth.
Idk, I could be completely reaching but this is my theory.
Also, guwon is my favourite himbo so I want their relationship to work out