Asad responds by wanting to hold her hand. My opinion is that in that moment, just when he hears Zoya's words, he decides to complete their story and that is why he is about to hold her hand in his. It wasn't merely a gesture of consolation but rather it was his response to a wake up call in Zoya's words. It seemed like he realized the finality of decisions and time, he realized that life doesn't offer multiple chances and that when you yearn for something, you should use the chance to make it yours. It was an affirmation that he desires to complete her and that she, too, fill the void in his life- he was offering her his hand for life.
He retracts his hand because he sadly realizes that if she intends to go back to New York, there is no point in taking such a bold step at the moment.
What did you think when you saw the scene? Am I reading too much into it- did he only mean to support her or did he mean to hold her hand as a life partner?
ps: I liked how they pulled the dialogue directly from the mangalpur background song O
Saiyyan: meri adhoori kahani, lo dastaan ban gayi