In a 2009 piece in The Weekly Standard, Sam Schulman argues that gay marriage replicates “a very limited, very modern, and very culture-bound version of marriage. Gay advocates have chosen wisely in this. They are replicating what we might call the ‘romantic marriage,' a kind of marriage that is chosen, determined, and defined by the couple that enters into it.”

This isn't what marriage has been through most of human history. Instead, marriage has taken the particular shape it has because it is part of a larger network, the kinship system.

One of the things marriage has done is to force men to respect the chastity of women until sex becomes socially acceptable within marriage. Schulman thinks that “it is a scandal that homosexual intercourse should ever have been illegal,” but adds that now that it is legal “there remains no extra sanction—the kind which fathers with shotguns enforce upon heterosexual lovers.” He comments sardonically, “I am not aware of any gay marriage activist who suggests that gay men and women should create a new category of disapproval for their own sexual relationships, after so recently having been freed from the onerous and bigoted legal blight on homosexual acts. . . . [D]eclaring gay marriage legal will not produce the habit of saving oneself for marriage or create a culture which places a value on virginity or chastity (concepts that are frequently mocked in gay culture precisely because they are so irrelevant to gay romantic life).” 

Because gay marriage doesn't bear the burdens of virginity and chastity, it doesn't bear the burdens of real marriage which, Schulman argues, even today are “honored in spirit if not in letter, creating for women (women as modern as Beyoncé) the right to demand a tangible sacrifice from the men who would adore them.”

Because gay marriage detached marriage from the kinship system, incest prohibitions have no weight: “If Tommy marries Bill, and they divorce, and Bill later marries a woman and has a daughter, no incest prohibition prevents Bill's daughter from marrying Tommy. The relationship between Bill and Tommy is a romantic fact, but it can't be fitted into the kinship system.”

In sum, “in gay marriage there are no virgins (actual or honorary), no incest, no illicit or licit sex, no merging of families, no creation of a new lineage. There's just my honey and me, and (in a rapidly increasing number of U.S. states) baby makes three.”