Most arranged marraiges are based on respect etc.. that's fine. But the foundation of this was emotional blackmail and duplicity. Not to mention a disease that prevents a normal marital life. In most arranged marriages they start out with that hope that they can eventually get to that consummate love. But here their relationship is already handicapped.
The problem is Naina is not clear about why she wants that relationship. Just to fulfill her patni dharam? Technically hindu marraiges are consecrated to produce children. This marriage is already going to prevent her from fulling her "dharam". Karan opened the wedding knot. He didn't even tie the manglasutra. So there has to be something more that makes her feel so strongly about staying in this relationship.
I guess I am a little bit offended by the glorification of patni dharam when you've been duped and generally treated poorly. Talking about regressive concepts, to me that's regressive. There is nothing wrong with wanting to make a relationship work. But both people need to want to make the relationship work.