this is not a spoiler, or nor am i having any inside source or information.
its my point of view. of why the Nikha between Asad and Zoya will happen.
Tanveer declayed to Zoya what she wants Asad, and Asad is totaly clueless about Tanveers true face.
Zoya has not even accepted to her self that she loves Asad, but she indirectly her love for Asad to Tanveer, Zoya is not fighting Tanveer to protect Asad, she is fighting Tanveer for her love.
Tanveer is very smart and cunniving, and Zoya does not stand a chance again her. But Zoya's confidance in her love and her ability to not give up fighting for something that is most dear to her will will find a way one way or another to bring Tanveer true face and intentions before Asad and his family.
Tanveer said she knows the nature of men, and she has the knowledge to melt any man even if he is of stone. But she has overlooked that Asad Amhad Khan is not like other men. Tanveer thinks she can seduce Asad, she has already tried and has failed.
Tanveer over confidence in her own abilities with men and her desperation are going to he her biggest down fall. also he has no idea what type of man Asad Amhad Khan really is.