Should we legalize straight marriage?

Yglesias observes Ross Douthat's struggle to make a rational point against gay marriage. Douthat:

lifelong heterosexual monogamy at its best can offer something distinctive and remarkable — a microcosm of civilization, and an organic connection between human generations — that makes it worthy of distinctive recognition and support.

Yglesias leaves aside that this is ideological garbage, and makes an even more obvious point:

The natural thing to observe is that very little of our current legal architecture of marriage has much to do with this. Actual marriages in 21st century America aren’t required to be lifelong or monogamous. Douthat concedes as much:

Or at least, it was the Western understanding. Lately, it has come to co-exist with a less idealistic, more accommodating approach, defined by no-fault divorce, frequent out-of-wedlock births, and serial monogamy.

So at this point we’re upholding an ideal of lifelong heterosexual monogamy by legally requiring the heterosexual part, but not the lifelong or monogamous part. The unfairness of such a standard seems both obvious and overwhelming.

Banning gay marriage is how (some) straight people kid ourselves that we haven't reduced the legal incidents of marriage to, basically, a voidable contract.

... as Douthat’s piece makes clear, the status quo is really a cop out. Instead of holding heterosexuals up to a rigorous standard of conduct--no divorce, harsh & unforgiving attitude toward infidelity--we’re going to discriminate against the gay and lesbian minority and then congratulate ourselves on what a good job we’re doing of upholding our ideals.

Obviously, the real solution is to outlaw heterosexual marriage. Straight people have a grotesquely high divorce rate, and the phenomenon of stepparenting and single parenting among straights has become an epidemic. A child needs a mother and a father, and it's abundantly clear that this cannot be accomplished through the institution of straight marriage.