Heyy guys!!! wake up and remember the moment when both arzoo and sahir share the moon stare separately although sitting beside each other they are unaware of each other's presence, arzoo says that moon never leaves us and is always there for us like a humsafar where as, Sahir says"har haseen chehray kay peechay aik aur chehra chupa hota hai....and so many other things.
so that haseen chehra was definitely zeenat and also the dosra chehra, so maybe she betrayed sahir still the realities are half told, don't forget this folks, if this was not the case sahir would be sitting beside zeenat crying but his tone is different he wanted to fulfill a promise even if she has betrayed him, my assumption ofcourse.
Mallu