Before we judge Zoya, we have to remember a few important facts.
1) Zoya is not all knowing; in this case, us, as the audience are. She does not really know anything except Imraan and Najma loving each other. She also does not know Imraan or Haseena Bi that well, she has no idea what lengths Haseena Bi (HB) could go to. What she sees is herself helping two lovers, one of whom happens to be the best friend she loves like a little sister, get together.
Also, Dilshad asked Zoya to find a husband for Najma, and Zoya sees Imraan as someone who could make Najma happy, the way Asad makes Zoya happy.
Her exposure to Imraan and HB is very limited. She has seen Imraan stand up for Najma, but she has not seen him keep quie with Nikhat. Also, while HB seems to be irritating and obviously not the best MIL, we have to remember another important point here.
2) Family dynamics. Zoya has never lived in a joint family, she has no idea about what occurs in one, and people can't expect her to. She grew up in the US with Zeenat and Anwar as basically the only family she knew. Then she came to India and lives with the Khans.
The delicacy of this situation is going over her head. Her reaction is actually understandable here, and only, if you know, as we do the whole situation will you see her actions as wrong or creating trouble.
Of course Zoya didn't understand where Asad was coming from. She doesn't understand this relationship that the two households have, and if you notice, throughout the show, so far, she has hardly been exposed to them. Most of her interactions with the other family have been completely superficial. She only knows what she has been told and guessed. In fact if you remember much earlier in the show, she wasn't able to comprehend the consequences of making Asad and Ayan meet up. Her familial experiences are very limited, and thats why she is unable to understand this situation.
She is only thinking of 'her' family, Dilshad, Najma and Asad. She doesn't understand the bond Asad shares with his other siblings, and until the Ghaffur track plays out, she wont be able to do so.
Family dynamics and values are learned. Each family is different. You can't learn these things with out being in the situation yourself. Heck, I myself don't understand family dynamics with joint families.
As someone who has grown up outside my home country and away from it all, I can definitely understand and relate to Zoya.
3) Zoya has always meddled in Najma's business, she has always stood up for Najma, spoken for her when she was scared of Asad's reaction and tries to look out for her. Najma sees Zoya as someone who will always be in her corner, and hold her hand.
Currently Zoya is only thinking of making Najma happy. She can't stand to be happy if Najma is unhappy, this is why I'm guessing she is pushing for the Najran nikah. She sees this wedding as something which will make both Najma and Dilshad happy, Najma will get married to the guy she loves and Dilshad won't have to worry about finding a groom for Najma.
4) Zoya doesnt truly get the in-laws concept. She has never experienced the situation herself, Dilshad is like a mother to her, and Najma like a sister. She has not been exposed to what a Desi marriage is truly like. We saw it from her wishlist. Zoya was, like any other young Desi girl, living in between two cultures, a western and desi one, looking for the perfect guy. She has not considered the 'in-law' situation and its not as important to her. She wants a good partner for Najma, the way Asad is a good partner to her. Also, she still hasn't had to consider it, Dilshad and Najma to her, are not her in-laws. She has for long, considered them her family.
She has dismissed HB because she truly doesn't get the relationship, the dynamic. She thinks that as long as Imraan and Najma are happy, everything is hunky dory.
Someone who isn't exposed to in-laws won't be able to understand their significance, if you've grown up in a desi culture, its something you get exposed to, even if you live in a nuclear setup, but a lot of my friends who I know have lived in a set up without being exposed to this type of relationship don't understand the importance.
5)This brings us to my next point, Zoya has always spoken up for what she believes in. Its to an extent, a cultural thing, us expecting her as the 'Bahu' of the KV to keep her mouth shut. We have to remember though, she's grown up in New York, and her values, and ideas are impacted by both Indian and Western culture. She stood up for Mariam, and now she sees herself standing up for Najma's feelings. We sympathised with her in the Mariam track because she was standing up for what was right. We have to remember though, that Zoya is under the belief that she is helping Najma. If we had been unaware of what was going on in the other household, we probably would not have bashed Zoya as much.
We actually see a beautiful portrayal of cultural concept here, our personal cultures make us who we are. Zoya grew up alone and independent as a result, but also outspoken. No one ever stopped her from speaking out. We see someone who is on the brink of two cultures, and trying to balance both. This is what attracts me to Zoya as a character the most.
6) Zoya's exposure to marriage is limited to what she has witnessed between Anwar and Zeenat. Our idea of marriage and love comes from what we are exposed to as children. We learn from what we grow up observing. Se has not grown up in a dysfunctional family, and she probably never had to deal with extended family. Her idea of love is also probably a slightly westernized one, Zoya has always been a romantic at heart. We see her portrayed as someone who views love as something which can conquer everything.
Her first dealing with love is with Asad, and well, in he end everything seemed to work out for the two of them. She honestly believes Love conquers all, and shes so happy she has found her one true love, and wants the same for Najma.
I'd like to end by saying that, Zoya here was neither wrong nor was she right, she was simply doing what a number of us, including myself would have done in this situation. No one is always right in real life, but just because we are not right doesn't mean we're wrong, no situation is black or white, usually its grey. I honestly love the portrayal of this character, because to me, she is just a good person, who can make mistakes, who doesn't always come out on top, some one who stands up for what she believes in.
I don't actually find her all that annoying, but I relate to her in many ways, because she is imperfect, just like every other person I know.
If you've found Zoya's character annoying from the start, the chances are you'll never like her, and thats fine, all of us are entitled to like whichever character we like.