No MC 'can' just leave her and let her die. The oath doesn't require him to protect Zhu Que. It only requires him not to do anything harmful to her, basically. Also, she is a child of the plane, so shes not much of a weakness.

A great novel so far with no super bad things about it. Hope the author doesn't drop it! Upload rate most definitely a plus though, 1 a day is hard to find for new novels.