I've been wanting to make a post on Najma for some time, so here it goes :). Najma is a character that I've always had a soft spot for. This isn't a defending or bashing post, but just one trying to understand her character and viewing things from her eyes.
With the whole Imran thing, I don't think Najma is selfish, but I do have doubts on her love for Imran in the sense that she could be mistaking it for love (but I'm still waiting for the whole thing to play out.) In my opinion I think she is holding on to Imran due to her own insecurities. She has physical insecurities (her weight) and emotional ones (daddy issues).
We have seen since the beginning that Najma has always had a problem with her weight. She has always been self conscious about it. On the night of the shooting star she wished that she would lose weight and if she couldn't then for someone to come into her life and love and accept her just the way she is. Imran came into her life and fell in love with her. She felt accepted by him. From what we've seen, no one came into Najma's life after, and three years is a long time for someone to move onto someone else. Maybe no one else liked her for her. I don't think Najma is someone who would want an arranged marriage. At least from what I have been able to tell she has always wanted a love marriage (remember the wish and ishq wala love).
Now to her emotional insecurities which I think play a bigger role. Just like Asad, I think Najma has some major daddy issues. I have seen it from the beginning of the show. She has showed bitterness towards her father and other siblings. When Najma told Dilshaad of how her siblings would come in big cars while her brother would carry her on his shoulders walking her to school, I could sense it from then. I have actually really felt for her because I can understand how she must feel seeing her father with his other family living happily with all the luxuries and their family being complete, while her family is incomplete and and knowing it always will be. Asad still got to spend some time with his father and experience his presence, but Najma never got the chance. She has no idea what a father's love feels like. When Dilshaad came home from the hospital and Rashid came to their house for the first time, we could see how emotional Najma was (I actually had cried during that scene, it was one of my favorites). That has been the only time I have seen an interaction between the two. Asad has interacted with his other siblings and they have showed him never differentiating them. But we have never seen Najma interact with them and I think there's a reason to it. Everytime Najma has come face to face with her sisters she has felt uncomfortable. When the girls were signing up for the fashion show and NIkhat turned to face Najma and smiled and was about to say something, Najma turned around and walked away. Even at Asad's nikkah, we could see Najma hesitantly smiled at her siblings. Somewhere deep inside she has always resented her other siblings. And it's completely understandable and normal for her to feel that way.
All these things bring me to another reason why she holds on to Imran. All her life she has heard people taunting her mother. Telling her how no family would ever marry their children to a family whose father left their mother (the whole 'chori hui aurat'). She has seen and heard insults hurled at her mother even to the point others (Razia and Shirin) cursing her and Asad. It's probably really messed with her head. Najma might feel if she lets go of Imran, no one will want her and maybe people are right (as earlier stated, no one came into her life within the three years after she left him). And she probably has a fear of what everyone has said of coming true. Since her other siblings have a father over their head and no one has ever bothered their family, it will be easy for them to get other proposals and find people to marry just as things always have been easy for them.
I'm actually really enjoying the current track because so many different relationships are being explored and we are finally getting to see the depth of other characters. Many relationships are being tested as well. Brother-Sister, Brother-Brother, and Father-Daughter. I'm really hoping this Imran-Najma track brings light to new relationships and the writers move forward and show the relationship between Najma and Rashid and how it affects it (even though there isn't much of a relationship there) but it is the perfect opportunity. We see how Asad is torn between both sisters, but how about the father. If Najma and Imran wedding happens, will Rashid come to give his daughter blessings and give her away just like he came to Asad's to tie the Sehra on him (for a girl this is probably one of the most important moments of her wedding day, her father putting his hand on her head and giving her away)? I would really like to see something of the sort, maybe Najma expressing her desire for her father to give her away or asking him, him denying her, and then seeing her reaction to it. I have always wanted to see more of Najma and Rashid scenes and their relationship being explored so I'm really hoping for it to happen now. And how Najma will react if she comes to know Asad talked to Ayaan and put Nikhat's happiness before hers (Asad is the only male figure in her life, a brother and a father)?
This is just my opinion on the current track and Najma's character though.