Oh, BTW, I remember reading another wuxia story where the nephew of the sect leader was discovered to be half demon. The demon clan would look for humans to mate, then raise the children to disguise themselves as full humans and infiltrate the sects.
My theory is that the unfinished story would have revealed that the FL is similarly a half demon and her tales of woe were falsified to pique the ML's interest. Her running to the demons in the beginning was simply to coordinate further infiltration methods and when caught, she and the demon lord improvised.
Su Luxia will reveal all, save the sect, and cause the ML to realize how much he overlooked her. Or something like that.
Just a theory, mind you.