I think that Hamid has rendered a portrait whereby nostalgia is seen as a human emotion, but one that is dangerous when it is the predominant emotion coming at the cost of others. For Changez, his disillusionment in both America and Erica results when both see their own nostalgia as the only means by which the present and the future can be constructed. In this light, Changez realizes the pain of nostalgia when it is the only guiding force to constructing reality. Hamid speaks of this reality in terms of resistance to being "monolithic:"
People and countries tend to blur in my fiction; both serve as symbols of the other. Which is not to say that my characters are chess pieces: I see my characters as fully human, not as mere motifs. The countries in my fiction are far from monolithic and are capable of envy, passion, and nostalgia; they are, in other words, quite like people, and I try to explore them with that sensibility.
For Hamid, the essence of being human is possessing the capacity to not be monolithic. The multidimensional nature in which consciousness is constructed is one in which human experience features many different emotions. The danger that Hamid wants the reader to draw from nostalgia is when it becomes the only emotion in which human existence is constructed. In this light, Hamid's characterization of Erica and America is when nostalgia guides them, Changez finds himself marginalized as a result. Even Changez himself recognizes the danger in nostalgia when he yearns for Erica despite reality. He understands such hollowness when he pretends to be Chris during sex. It is at this moment when he feels estranged from himself, a conclusion that Hamid wants the reader to appreciate when nostalgia becomes the driving force behind consciousness.