Chinese and other foreign students in the United States often feel misled and even betrayed by Americans who seem so friendly at first but then turn out to be uninterested and perhaps cold and distant.
Most Americans will fairly readily meet new people in a warm, friendly manner. They will smile, say hello, introduce themselves, and carry on a friendly-seeming conversation about some simple topic.
Later, though, those same Americans may forget entirely about the interaction, and not even remember they have met the new person.
This leads some foreigners to conclude that the Americans are superficial, devious, dishonest, “not really human.”
Foreigners need to realize that the initial, warm greeting and conversation is part of a social ritual. It does not normally convey, to other Americans, any special interest or any intention to pursue the relationship later.
Foreigners need to pay particular attention to what is said in these initial conversations. If the conversation goes into some detail about people’s personal situations, or if it contains explicit statements about seeing each other again, then the foreigner can suppose the American has genuine interest in meeting again.
Otherwise, the apparent friendliness is simply polite behavior.