Jukebox musicals stand or fall on the strength of the songs and the ability of the performers to deliver on them. Plot and character often feel bolted on. In the case of “Breaking up is Hard to Do,” the music of Neil Sedaka forms the reason for the show, and the Centre Stage cast in Greenville, SC, deliver. I rather wish the book by Erik Jackson and Ben H. Winters gave the performers more scope for their talents. I feel that way about a lot of jukebox musicals. The plot is “Dirty Dancing” meets “Grease.” Set at a Catskills resort in