Complex sentence: Joanie and Chachi see Pinky mooning over a photo of Fonzie: she's clearly not as over him as she pretends to be, but he insists that his days of pining over her are over.
Split into simpler sentences: Joanie and Chachi see Pinky mooning over a photo of Fonzie. Pinky's clearly not as over him as she pretends to be, but he insists that his days of pining over her are over.