The song that’s become Paily’s theme was written specifically for them!!! 

“Guys Like Paige” by Joel J. Richard is an instrumental piece created specifically for the show. The song plays during several Paily scenes, including Paige’s rain apology, Emily and Paige’s window seat kiss, Paige telling Emily about coming out to her parents, the pool kiss, their romantic scene on the train, and when Paige says ‘I love you.’ The title refers to the window seat scene where Emily tells Paige that when she was still pretending to be straight  ”she would look for guys like Paige” 

This was on the Pretty Little Liars wiki page and now I love this show even more <3333