It is a namesake relationship he himself has confessed that, for his family he was responsible for them, I refused to accept that MB really cared for him because the only thing he is for her is the head of the family who will give them money and security nothing more nothing less, Mariam always has Haya before this kaand haya was good to her, but who does Murtasim had?? To feel the love he has for Meerub?
Behen, Haya ko achha mat kaho
This kaand happened bcz of her selfish one-sided infatuation for Murtesim only!
Maryam sympathized with her when it was her rishta that was in discussion & she suggested Haya to talk to Murtesim to stop marriage! Haya ne toh ulta Maryam ko hi phasaa diya, woh bhi yeh jaante hue ki Maryam kisi aur mein interested hai(she told Haya, main apni pasand ki shaadi karungi)!