Billy and Katie Joel

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Although there is a 32-year age gap between Katie and Billy, they hardly notice. "He has this job that's allowed him to be really immature for a long time—rock star," Katie says. "And I happen to be more mature for my age, so we meet somewhere in the middle."

The age difference doesn't matter to Billy, either. "I've said this before—I would have married her if she was 30 years older than me," Billy says. "When it works and it clicks, you don't fight it. You go with it."

Katie says she also has a great relationship with Billy's daughter, Alexa Ray. "She was my maid of honor at my wedding, actually," she says. "And I'm always impressed by her. She has so much talent and grace, and she's just really special."