Have you read his past? Its been pretty traumatic for him and he may be gay, but Yuyang feels more comfortable loving one person and one person alone. Not to mention Lihuan IS straight and has always seemed so to Yuyang. Hes afraid Lihuan is so socially inept that his feelings are muddle for romantic ones
Stable people don't really date anyone just because the other person is interested. He likes someone else and the emotional wound is still too raw and obviously wants a meaningful relationship with both people feeling it. If you can move on THAT easily, then you obviously did not like the person that much. Not even mentioning that Lihuan wasn't gay, so obviously he doesn't trust him all that much.
He doesn't dislike LiHuan...he said so. Does he not date? Does he not want a boyfriend? Just exactly what does he do? Hang out with his roomies? Here he has a drop dead gorgeous guy who really wants a relationship with him and he keeps coming up with these flaky excuses. I realize LiHuan may be a bit awkward but YuYang comes across as a guy who doesn't have a whole lotta experience at love either