Zig Zagged: Eric lost his best friends in tragic circumstances, for which he blames himself; being around other friends or attempting to make new ones merely reminds him how much he'd rather still have the ones he lost. New friends are unsatisfying and pale substitutes for the friends he lost, as well as something he doesn't feel he deserves: his isolation is both penance and paying respect to his fallen friends.
Eric really is perfectly content in being alone.
Eric has friends and he's perfectly happy with his social life.
Invoked: Sarah, who wishes to be Eric's friend, tries to get him to admit his desire for it so he'd let her close.
Exploited: Jim manipulates/persuades Eric to do something by his wish of getting friends.