The plot of this story is definitely unique.However, I feel the creative team is making Ishana a vamp for no reason.
She is jealous, yes any lover would be in her situation, she is now plotting, yes but also realizes that her actions are mean, she is confused, anyone in her situation would be.
Lajjo is a real character too. She is a beautiful human being as per her nature and her brought up in a simple world. She is sacrificing because that's what women do in her village, she started loving Nikhil, very obvious in her situation.
Nikhil, as I see it, is very clear in his mind, can not and does not love Lajjo. He truly until now loves Ishana ( that's what he has been believing so far as there was only Ishana and no other girl in his life). He is missing Lajjo as in his situation anyone would, she was taking care of him without any expectation and he is also concerned about how her family would react to her going back. For that reason he is feeling bad, he is thinking that he pushed her to the edge that she made a decision to go back for good.
Now, most of us want Nikhil to miss Lajjo, fall in love with her, compare her with Ishana and bring her back and educate her.
In real life, at least that's how I believe, the interaction that leads to love is physical attraction, the compatibility and then come other things like status, education and family.
So far I have not seen any physical attraction from Nikhil's end, we have not seen any compatibility and the two families have a very different outlook towards life.
On today's date, Ishana and Nikhil match much better than Lajjo and Nikhil.
In my opinion, Nikhil should own up to his marriage with Lajjo, whether he loves her or not, give her proper chance to get education and have a smart outlook at the world and then consummate the relationship and eventually fall in love with her for who she is. To me, this is more realistic and a good answer to some of the snob members of his family.
Ishana is a beautiful girl, she will find love again once she gets the signal that Nikhil is not available any more.
I apologize for ranting my opinion here but would welcome criticism and comments with open heart.