Wei Zi is willing to be Erkang's wing room. Why can't the swallow?

Maybe it's an irresistible attraction between the opposite sex. Wei Zi is my wing room, but Erkang has that feeling for Wei Zi, but the swallow can't. It's like you are the apple of your parents' eye, which is irreplaceable by any child. This is a kind of pure love, which is fundamentally different from before. The front is the feelings between the opposite sex.