What counts as a good life? Philosophers see this as a profound and complex question, but to much of the rest of the world, the answer is simple. Movies, TV shows, fairy tales, novels, songs, and the advice of generations of parents have all converged on a straightforward formula: Find “The One” and commit to The One. Get married, the story goes, and you will live happily ever after.  

For a long time, social scientists seemed to be peddling the same message. At first, though, their studies were not very sophisticated. That has changed lately. Now, the very best studies – and there are many of them – are showing something very different from what we have been led to believe.