See I just started watching recently myself and I have to agree with KhatamKahani. It seems that Nisha wanted money and power, not just to live separately. Up until I point I understand Nisha and support her. If she can't live in a joint family, fine. If she wants Aditya only for herself, that makes sense as well. Her want for money makes sense to some extent as well. She enjoys parties and drinking. Good. She lives her life like she wants. Perfect.
But then in Indian culture such women are frowned upon. Females need to be docile, goody-two shoes, Sati Savitri types. Hence Nisha is a villain. And to exemplify that further they've added in this greed, power-hungry, bitch type actions. She pays goons to kidnap and rape women. She puts together acts to make her appear the goody-good girl while her husband is "evil" and two-timing her. She disturbs the shanti of the house. She uses her kids.
On the other hand we have the perfect Jhanvi. The perfect Indian female. She prays. She solves problems. She treats everyone with respect even if they don't treat her with respect. Family comes before career for her. She doesn't drink. She doesn't party. Even for a 20-something year-old she is so homely.
I don't have anything against either of them. But no one is one colour. No one is perfect. Yet in Indian TV shows, one must be perfect. There's no grey shade. There's no imperfect character. No. There's either hero or villain. And to illustrate that Nisha is Satan and Jhanvi is God.
Now you mentioned that Aditya can't have a relationship with Jhanvi without divorce. But you see in our Indian culture only physical relations are really counted as extra-marital. Not only that, but the male species can never be wrong. If they go outside their marriage to someone else it's the wife's fault. So in this case even if Aditya and Jhanvi do get into a relationship, it's Nisha's fault. On the other hand, as long as they don't consummate their relationship neither is wrong.
Sorry but I have severe problems with certain aspects of our culture, especially the degrading of women. And this show is a perfect epitome of everything that women can't do else it makes them look cheap, vulgar, and villainous.