I agree with you Suchi - many of us have an intuition that Mamu is Zoya's dad (and you've drawn together some good reasons for that).
Just wanted to add some more points to it though: (Which are open to debate)
1) Zoya is not related to Dilshad Aunty in any way...nor do I think that'll ever be the case. She is just a close family friend of Zoya's jeeju.
2) I'm not sure if Asad knows that Mamu is the reason that his parents were forced to separate/divorce. I don't think he would be leave Zoya for that reason...however, I do get the feeling that once Asad does fall for Zoya, the reason he will leave her is because Ayan has also fallen for Zoya and he'll want his younger bro to have her over himself.
3) Our other theory is that Humaira will not like Zoya because she marries Ayaan...
Just praying though that Asad-Zoya are together because they make a sizzling pair!