Falling in love with someone is the easy part. Learning to live with someone is the hard part. All romance starts with a spark of chemistry, but over time, some couples really complement one another, and others seem to want to kill each other. Is it just dumb luck? What separates those that crumble after seven months from those who end up celebrating seventy years? It’s either a complete fluke or they’ve figured something out. And since nobody looks forward to starting over again, what could we learn from them?