It's not necessarily wrong for Lu Xiao to do this, but there's one thing he overlooked—Gu Xiaonuan's own thoughts.
Gu Xiaonuan's own thought is that she wants to stay, to stay in Sea City.
Sea City is the place Gu Xiaonuan cannot part with the most; as for other people and matters, they are no longer important.
The matter of Lu Xiao's serious illness is not to deceive her, but Gu Xiaonuan also has her own considerations.
She will not agree to his conditions to inherit his family business just because Lu Xiao doesn't have much time left.
That would come at the cost of leaving Sea City, and how could Si Yuchen possibly agree to that?
They had just decided to form a family, and then they see such a future.
Gu Xiaonuan would rather let Lu Xiao return disappointed, hoping he can think clearly about what she truly feels towards him.
