With Amy in Sheldon's life (despite they still not being boyfriend/girlfriend), Bernadette in Howard's life, and even Raj now having a girlfriend (she being deaf so it doesn't matter that he can't speak to her), Leonard is the only one of the group who is currently without a significant female in his life. He doesn't seem to mind too much until everyone, even Stuart at the comic book store, constantly reminds him as such. And Leonard's air of desperation - as Amy refers to it - means that in his current state he is unlikely to find a girlfriend on his own. So Leonard reluctantly invokes the girlfriend clause in his friendship with Howard, meaning that Bernadette needs to find him a girlfriend. But will Leonard be desperate enough to continue to date Bernadette's choice of Joy, a friend from her self-defense class, a woman who talks about the hundred different ways she can rip his private parts off his body? Meanwhile, Sheldon fears that Amy's request for him to meet her mother is her way of saying that she wants them to become boyfriend/girlfriend officially. In light of that, Sheldon does whatever he can to eliminate Amy from his life except by telling her directly.