I think Ayaan does remember that Asad gave hasseena bi the flat, which is why he is having hard time understanding that why would Asad bring Najma's proposal to Imraan's house when he knows that Nikhat is in love with Imraan which is why he had happily given the flat to Hasseena bi, its Ayaan's immaturity that makes him say all this stuff. No brother is wrong in this situation they both want their sisters's happiness. Ayaan can't expect Asad to pick Nikhat's happiness over Najma, than again Asad cant expect Ayaan to be all happy about Najma getting Imraan, and not get angry.