He didn't think helping out the Goblin in keeping his Bride alive would give him repercussions like this - actually, he did think, he specifically told the Goblin this.
So for his rule-breaking, he was punished with remembering everything about his past life - and he did not like what he saw - he was the king from Nari's past life, and the Goblin's past.
He had killed his own family, sent those he loved to slaughter and watched the woman he loved die from his own actions.
He watched as he died from a poisoned tonic, he knew it was poisoned, but he continued - he just wanted her.
He was left in his tea shop, crying and in pain.
He had seen what a monster he was - or is, he hadn't decided on which.
