Hook up first, ask questions later. That’s modern love, right? We’ve got the freedom to get naked on a first meeting, without knowing much about our partners or feeling guilt about the intimacy. Recreational sex. Hooray!

In “Phoenix,” a dark one-act comedy that’s just opened at the Cherry Lane Theatre, Bruce (James Wirt) and Sue (Julia Stiles) reconnect at a New York coffee shop four weeks after a one-night-stand. Sue arrives with three news items to share: She enjoyed the sex. She doesn’t ever want to see him again. And she’s pregnant.

That last bit’s a shocker to Bruce, who’s gone through adulthood under the impression he’s sterile. When Sue, a traveling nurse, reveals that she’s made an appointment to terminate the pregnancy the next week, at her next job in the city of the play’s title, Bruce admits to an undefined compulsion to join her … and she reluctantly agrees. What could possibly go wrong?

At heart a story about emotional intimacy—our simultaneous need for, and repulsion from it—“Phoenix,” by Brooklyn playwright Scott Organ, features dialogue that regularly brims with wit. When Sue suggests the pregnancy was easily preventable, Bruce replies: “If you’re implying that my condoms were somehow old as a result of a lack of sexual activity on my part in recent, what, years, then, you know, you’re dead on.”

Still, it’s ultimately bogged down in a cookie-cutter message about risk-taking. Not the sexual kind, mind you, but the kind that comes with doing something brave, such as having a kid, or sharing your life. “No one is safe,” Bruce says, after Sue confesses her reasons for not wanting children. “And yet we have our lives to lead, don’t we?”

Stiles and Wirt are dynamic together, and their rapport is natural and easygoing—she even does yoga in the middle of their speakerphone chats. At least, I think they were speakerphone chats … director Jennifer DeLia could have managed matters with a firmer hand, particularly the awkward and lengthy scene changes (props to a pal, who coined them “pregnant pauses”).

Stiles, star of the “Bourne” trilogy and a vet of NYC stage work in Shakespeare (The Public’s “Twelfth Night,” in 2002) and Mamet (“Oleanna,” on Broadway), has the harder job, because Sue, with her desperately cynical world view, just isn’t likable. (“Oh my god, she needs to work out her s-it,” a frustrated female audience member told me, unsolicited, on our way out of the theater.)

You may fall head over heels for the lesser-known, delightfully deadpan Wirt when he confesses his seduction technique—he’s really a time-traveler from the future on a “sex vacation,” because “women from this era have a reputation for being kind of easy.”

You never feel his character is trying to manipulate Sue into keeping their baby, even though the play’s engaging and truthful-feeling climax transpires in the waiting room of the Phoenix abortion clinic.

“Phoenix” works best as an examination of modern mating rituals, where it’s entirely and realistically conceivable that you could have the intimacy of sex before knowing your partner’s last name. Or phone number. Or that you both prefer tea to coffee, but you keep making “coffee” dates because it’s what strangers do.

The play gets into trouble when it focuses, heavy-handedly, on a message we know all too well: simply getting out of bed in the morning involves a certain degree of risk, but sometimes, to paraphrase Bruce, you’re still living better if you drive instead of taking the train.

“Phoenix,” through Aug. 23 at the Cherry Lane Theatre, 38 Commerce St. Tickets: $56-$66. Call 212-989-2020.

Follow Robert Kahn on Twitter@RobertKahn