" In Monsters, Inc., all of our very different plots shared a common feeling—the bittersweet goodbye you feel once a problem”—in this case, Sulley’s quest to return Boo to her own world—“has been solved. You suffer through it as you struggle to solve it, but by the end you’ve developed a sort of fondness for it, and you miss it when it is gone. "

― Ed Catmull , Creativity, Inc.: Overcoming the Unseen Forces That Stand in the Way of True Inspiration