The story of these three is unique. In other stories, with the arrival of the wife, the girlfriend is usually projected as a vamp, jealous and revengeful. Here Ishana is no such person and totally in love with Nikhil. She is in a state of denial about her relationship being the same as before with Nikhil. Now who is responsible to put her in this state- our own cute and innocent Nikhil who is always trying to prove his worth to all the women of the family, is kind and also emotionally involved with Ishana. From his perspective he is only Laajo's friend and is very clear in his mind that this pact is to save Laajo's family's honor.
Ishana is not able to move on and is also held back by Nikhil's interference post marriage, and Laajo is falling in love with Nikhil where she is misinterpreting his kindness towards her as love.
In the current track, Ishana would come out of denial, if Nikhil does not run after her to provide explanation. Laajo would understand that Nikhil loves Ishana if Nikhil tells her clearly that look get busy with some studies and be on your feet and I will support you but I am in love with this other girl and can't leave/hurt her. Nikhil would come to his senses and who he should really be with if Ishana takes a stand not to meet up with him until he has sorted out his feelings and life and Laajo tells him to put her in another four walls where she is not rebuked for no reason and has a purpose in life.
I think the only sense for now is with Barkha who is trying to show Nikhil the reality but her ways of doing so are cunning, mean and evil that her purpose loses the meaning.
Just because we love Laajo and want to see her happy with Nikhil, we should not be putting Ishana down who has lost her love in the blink of the eye because of someone else's immaturity.