Changez recognizes a couple of things resulting from the discussion with Erica's mother about her condition. The first is that any potential hope of a relationship between both of them is going to be put aside for now. When Erica's mother tells Changez that she needs a "friend" and not "a boyfriend," it can be seen as a mother's warning in protecting a fragile daughter. While Changez never comes out and says it, I think that he realizes a bit of fear on Erica's parents' parts in terms of her mother's reaction. At this point in time someone like Changez could never be seen as a suitable match for their daughter given the state of the country at that time. Changez also recognizes that their relationship will never go back to that time in Central Park before he left for Manila. There will not be a sense of walking arm in arm after a picnic. Something has permanently changed and Changez realizes it from speaking with the mom, something that is confirmed when he actually sees her. It is here where there is a change evident in their relationship, something that is also on the horizon in terms of his relationship with America.