Why would this person not respond to my facebook friend request?

[Sammy]

There is this girl who was in one of my college classes last semester and im pretty confident that she liked me. Anyway, i added her on facebook yet she never respond to my request by either confirming or ignoring it. Is she doing it on purpose? Could she have not noticed?

[Naina]

don't get depressed man ......may be she is busy and she don't have time to check her facebook.
or its also possible that some guy don't allow her to make friends on faacebook...like guys
that guy would be her brother or boyfriend ..........so just clam n wait ,

[suspended-2z]

if you find her attracting then dont keep on adding her leave the friend request by her,then she will think that your not stalking her and she will then add you i hope she does tbh