Both Jaekyung and Dan grew up in terrible conditons but the major difference is that Dan grew up with love and care. Jeakyung doesn't know how to receive and express love, only violence. That's not an excuse, that's just a fact. With him realizing his feelings for Dan, he has an opportunity to learn, grow and change. What he decides to do about that matters more than where he came from. We can forgive someone who didn't know any better, but we can't forgive someone who consciously decided to do nothing about it.
Both Jaekyung and Dan grew up in terrible conditons but the major difference is that Dan grew up with love and care. Jeakyung doesn't know how to receive and express love, only violence. That's not an excuse, that's just a fact. With him realizing his feelings for Dan, he has an opportunity to learn, grow and change. What he decides to do about that matters more than where he came from. We can forgive someone who didn't know any better, but we can't forgive someone who consciously decided to do nothing about it.