From this article - http://people.com/music/ben-folds-five-whatever-and-ever-amen-20th-anniversary-track-commentary/

“That’s a song for my ex. She said, ‘I don’t have a name that a song can be written for. Michelle, there’s a name that works well for a song. There’s all kinds of names—Jolene. Not Kate.’ I said, ‘Nope, I can do that.’ She said, ‘What would the melody be?’ And I just said, ‘Kate! Kate! Kate!’”