After all, she and Milind loved each other first. Also, how would someone feel if their mother is in the mental asylum and the rich dude who impregnated her has been living peacefully? Whereas examine all the good fortune that has been Prachi's all along
a) She was raised in the arms of wealth as the legit daughter of her father (unlike poor Ayesha who had to go through tough times while growing up)
b) She always had Neev's love before Milind came on the scene
c) Now she actually has the love and affection of two men and the rest of her khandaan. Whereas Ayesha, is still poor little Ayesha, shunned by thr whole world.
Yes, Ayesha is always plotting etc, but noone realizes her inner pain and conflict. If you are rejected by the whole world while you are growing up, there is no way you can come to terms with it easily. So have a heart guys...