At least they're not blood related, yu knew he wasn't blood related at a young young and A knew too after yu realising his feelings for A , he went away from his home when he was in young too. As kids , they don't even know what even feelings is like so what's the problem. If this was a story of a couple knowing each other since they were born , their family bring besties and treating then both like their kids , then would it be like incest too ? The parents were understanding , because they knew Yu's past and how nice he is, the parents are open minded. Maybe you didn't understand because you're not familiar with this types of situations and story that's all.
The whole story is beautiful, until the story of the brothers came up. I wanted to understand this love story, but I can't. He saw him born, took care of him, and they lived together like brothers for many years, Also, when she realized her "feelings," her little brother was in high school, the fuck, and that was the last straw, which made me skip the parts where they appeared was when his mom told him they weren't going to test him on anything, Even though they didn't understand, they still wanted their "son" to be happy. Are you kidding me? What parents would say that? No matter how understanding and open-minded they were. And absolutely no one finds it questionable? And for a moment I thought Yiyi is right to be surprised, but since he's in a "forbidden" homosexual relationship They didn't want to make him look like a whiny, judgmental woman.