By Maureen Dowd — The New York Times.

When does a woman go from being single to unmarried?

As my friend Carol Lee, a Politico reporter, observes: “It seems like a cruel distinction and terrifying crossover.”

Single carries a connotation of eligibility and possibility, while unmarried has that dreaded over-the-hill, out-of-luck, you-are-finished, no-chance implication. An aroma of mothballs and perpetual aunt.

Men, generally more favored by nature as they age, can be single at all ages. But often, for women, once you’re 40 or 50, or simply beyond childbearing age, you’re no longer single. You’re unmarried — meaning it isn’t your choice to be alone. There are post-50 exceptions. Consider celebrity examples: Samantha in “Sex and the City,” Dana Delany, Susan Sarandon and Madonna are seen as sexily single.

But if you have a bit of a weight problem, a bad haircut, a schlumpy wardrobe, the assumption is that you’re undesirable, unwanted — and unmarried.

White House officials were so eager to squash any speculation that Elena Kagan was gay that they have ended up in a pre-feminist fugue, going with sad unmarried rather than fun single, spinning that she’s a spinster.

You’d think that they could come up with a more inspiring narrative than old maid for a woman who may become the youngest Supreme Court justice on the bench.

In the initial accounts about Kagan, she seemed to have an appealing swagger, posing as a judge for her yearbook, bragging about what a “famously excellent teacher” she was, bantering with the Supreme Court justices as solicitor general, smoking cigars, drinking beer and playing poker. And she had an endearingly ditzy streak: One friend told how she would get so consumed with work, she sometimes parked her car and left it running all night.

But there were also the whispers — is she or isn’t she? — and the guys in the White House got all defensive, protesting too much that she isn’t. If roughly one out of nine Americans is gay, why shouldn’t one out of nine Supreme Court justices be? After all, President Obama has quoted Oliver Wendell Holmes as saying that “it is experience that can give a person a common touch and a sense of compassion; an understanding of how the world works and how ordinary people live.”

Kagan has told a friend in the West Wing that she is not gay, just lonely. Even so, that doesn’t mean her sherpas in the White House, in their frantic drive to dismiss the gay rumors, should be spinning a narrative around that most hoary of stereotypes: a smart, ambitious woman who threw herself into her work, couldn’t find a guy, threw up her hands, and threw herself further into her work — and in the process went from single to unmarried.

It’s inexplicable, given that this should be Kagan’s hour of triumph as potentially only the fourth woman ever to serve on the highest court.

And it’s a pathetic contrast to another big news story in Washington — the resignation of Representative Mark Souder, Republican of Indiana, a goober who preaches sex-abstinence and couldn’t abstain from sex.

The conservative Christian lawmaker is both morally and physically repellent. But he effortlessly benefits from Henry Kissinger’s dictum about power being an aphrodisiac. He had an affair with a younger babe who worked for his district office — “part time,” he ludicrously stressed. They had assignations in state parks and boat launches, and in a particularly delicious bit of hypocrisy, the pretty mistress even interviewed him on a promotional video about the importance of abstinence.

Another case of a family-values politician thinking he knows what’s good for everybody else but exempting himself.

For some reason, Kagan’s depressing narrative is even more depressing because it’s cast in the past tense, as if, at 50, Kagan has resigned herself to a cloistered, asexual existence ruling in cases that touch on the private lives of all Americans.

It’s a disturbing echo of those Harvard Business School students who said on “60 Minutes” a few years ago that they had hid the fact that they went to Harvard from guys they met because it was the kiss of death with men who were threatened by more successful women. “The H-bomb,” they called it.

Why is there this underlying assumption that Kagan has missed the boat? Why couldn’t she be eager to come to Washington to check out the Obama-era geek-chic bachelors, maybe get set up on a date by Michelle Obama, maybe host some single ladies fiestas with Sonia Sotomayor, maybe even sign up for JDate with a new and improved job status?