I actually think this ending works well too. Hyesung can finally find peace knowing that he at least tried to forgive his mother, so he won't be left with regrets or keep wondering what might have happened if he had opened the door that day. Through that experience, he realized that even though he wanted to forgive her, he still couldn't completely overcome the pain of being abandoned. In a way, this gives him closure because he now knows the outcome for himself. As time passes, whether it's Hyesung or his mother nearing the end of their life, he won't have to live with the lingering "what if" of never giving it a chance.
I actually think this ending works well too.
Hyesung can finally find peace knowing that he at least tried to forgive his mother, so he won't be left with regrets or keep wondering what might have happened if he had opened the door that day. Through that experience, he realized that even though he wanted to forgive her, he still couldn't completely overcome the pain of being abandoned. In a way, this gives him closure because he now knows the outcome for himself. As time passes, whether it's Hyesung or his mother nearing the end of their life, he won't have to live with the lingering "what if" of never giving it a chance.