Over at the Institute for Family Studies, Nicholas Wolfinger, a sociologist at the University of Utah, has found that Americans who have only ever slept with their spouses are most likely to report being in a “very happy” marriage. Meanwhile, the lowest odds of marital happiness—about 13 percentage points lower than the one-partner women—belong to women who have had six to 10 sexual partners in their lives. For men, there’s still a dip in marital satisfaction after one partner, but it’s never as low as it gets for women,... (Skip) In an earlier analysis, Wolfinger found that women with zero...