[art credit to thekeythief on instagram] Here's the thing: Nancy only wants to piss off her parents and maybe cause some jealousy to her ex boyfriend Jonathan, and Eddie knows this, he knows that Nancy only wants to use him and that he has no reason to accept this, specially from a girl he barely knows. Yet he accepts to be Nancy's fake boyfriend until she lets go of this rebellious phase and gets bored of him, because he's curious to see what comes out from this. Maybe he himself will cause some jealousy in his crush, who just happens to be Nancy's other ex boyfriend, and maybe be doesn't mind being used by Nancy at all. Also, why does Robin look so depressed every time he and Nancy appear together?