In the rush of excitement about today’s Supreme Court rulings overturning a key part of the Defense of Marriage Act and enforcement of Prop 8 in California, Slate has produced an appalling little article pointing out that many gay relationships and marriages are not, in fact, monogamous. She describes, for example, Dan Savage’s self-description as “monogamish.”

What’s appalling is not this key point (although it’s questionable), but the author’s titillated shock at those adventurous gays and smug certainty that no such arrangements could ever be made among straight couples. “In some far off ideal world,” she writes, “this kind of openness may infect the straight world, and heterosexual couples actually start to tackle the age old problem of boring monogamous sex. But do any of us really believe that?”

We will, for the moment, let slide the unfortunate use of the word “infect” to describe something gays might be doing to straights. Instead, let’s focus on this 1950s attitude about women’s sexuality. In the era of What Women Want, 16 years after publication of The Ethical Slut, nearly a decade after the end of Sex and the City, who is still astonished by the idea that a woman might embrace non-monogamy?

Relationships involve choices, not all of them easy. Monogamy is a choice that many couples make. But it’s a choice, not a gender- or orientation-based inevitability. By now it should no longer be controversial or surprising to recognize that women have their own sexual desires, and their own agency in responding to those desires. Monogamy is no more an inevitability for straight women than non-monogamy is for gay men.