In the 3 part Mary Elizabeth ( also a friend of the group ) is asking Charlie if he would like to go to the Sadie Hawkins dance with her. And he said yes!
I was a bit suprised because didnt he was in love with Sam. And i thought why do you go out with a girl, when you like someone else.

http://www.allocine.fr/personne/fichepersonne-19590/filmographie/