After Marianne Gingrich, Newt’s second missus, claimed that he’d asked her to stay married even as he continued an affair with his now wife, the Republican presidential hopeful vehemently denied the claim—but not before the open marriage debate was sparked anew. In fact, people were far less outraged by the alleged affair (which he has not denied) than they were that he may have sought permission for sex outside his marriage. That’s because open marriage tends to sit funny with most Americans. The arrangement became more common in the 1970s as the divorce rate climbed toward its all-time peak, but after 1980 Americans picked up the monogamy torch again, and it has burned hotter each year. In spite of the fact that 5 percent of American marriages meet the definition of “open,” a vast majority (81 percent) believe that it’s “always wrong” for a married person to have sex with someone other than his spouse under any circumstances. Meanwhile, in Britain people have grown ever more tolerant of adultery. According to experts, a true “open marriage” must be mutually agreed on by a couple, though it traditionally goes more like this: The male has the affair, and the woman puts up with it. We’ve come a long way from the 1600s when adulterers were put to death, but today’s affairs are landing some people in jail; in some states (like Arizona), adultery can merit a misdemeanor, while in some (Michigan) it’s a felony. So, no matter what husband and wife mutually decide, crimes of the heart are sometimes truly criminal.