So they lived happily ever after. Seoyo forgave Narye/Chaehon because he realized he loves him and Chaehon actually regrets everything he did in the past and suffered 5 lifetimes without Seoyo just to see him again.
JUST KIDDING AT THE LAST CHAPTER SEOYO FOUND OUT CHAEHOJ WAS NARYE AND RELIVED HIS TRAUMA ALL OVER AGAIN AND KILLED HIMSELF BUT SINCE HIS SOUL IS TIED TO NARYE THEY SEE EACH OTHER AGAIN AND AGAIN WITH SEOYO ENDING UP KILLING HIMSELF OVER AND OVER AGAIN.
I love the ending bevause if it had ended in a tragedy like "10 year I loved you the most" where the MC just died miserably I would be so sad for SeoYo I am just happy he is happy and Narye is happy since he got what he wanted