“I heard from editors early on that I, quote unquote, ‘lean on my dialogue,’ ” says third-time novelist Theresa Rebeck, “—and I thought, why, yes, I do. You would, too, if you were me.”

You’d do well to: Rebeck is the author of more than a dozen plays produced in New York City, on Broadway and beyond, including “Omnium Gatherum,” which was nominated for a Pulitzer Prize. She’s the award-winning TV writer (“NYPD Blue”) who created the NBC primetime series “Smash” (2012-13). Her dialogue-driven novels include Twelve Rooms with a View, Three Girls and Their Brother and her latest, I’m Glad About You, which opens on a conversation at a party in a New York apartment:

“But what is a demimonde, anyway,” said Alison.

            The guy she was talking to, someone named Seth, smiled like he knew the secret answer to that. He wrote a column about celebrity bedside reading for Vanity Fair and his name had shown up once even as a byline on a feature for that esteemed publication. Alison did not fully realize the import of this accomplishment but he did.

            “The demimonde, actually,” he told her. “There’s only one of them, grammatically speaking.”

            “What?” said Alison, confused.

            “The demimonde. It’s called the demimonde. Not like a demimonde, not a demimonde like there’s a lot of demimondes and this might be one of them. There’s only one to begin with, so it’s the.”

Alison Moore moved from Ohio five months prior intending to become a professional actress. That meant leaving behind high-school boyfriend Kyle, who possessed an idealistic and incompatible goal of becoming a doctor and moving to South America to treat war refugees. Of course, at this early stage, neither is living their dream: Alison is a professional cater waiter, while Kyle practices pediatrics in a soulless Cincinnati suburb.

“[I’m Glad About You] is about two people who are in love before the book begins and can’t let go of each other—their lives would be easier if they would let go, but they can’t,” Rebeck says. “As they spin in very different directions, they judge each other’s choices, in light of what they know about their youth, and they stand in each other’s judgment.”

No one captures the clash between Midwestern morals and East Coast intellectualism quite like Rebeck, who is from Cincinnati. Debates arise as Alison experiences her earliest successes as an actor, Kyle becomes a husband and father, and each compromises to achieve their goals. All the while, their irresistible entanglement endangers what they’ve striven for.

“It was a spectacularly delusional dance,” she writes. “He truly hated her, and had already laid full responsibility for the creeping mediocrity of his marriage at Alison’s feet. But even as he privately nursed this whisper of blame—for a disaster which hadn’t even occurred yet—he simultaneously drowned, every chance he got, in the memories of their time together.”

One senses no easy resolution for the ill-starred pair, rendered with the care and nuance of Rebeck’s most unforgettable characters in prose and plays. More than a love story, I’m Glad About You is rich in cultural criticism, feminism, psychology—yes, dialogue—and especially humor. Rebeck trains a shrewd eye on interpersonal relationships, offering up side-splitting appraisals of everything from Alison and Kyle’s chaste high school relationship (“the most extended and painful dry humping the universe has ever seen”) and suburban Ohio (“the whole northwestern suburban sprawl around Cincinnati was a veritable slap in the face to Betty Friedan and the seminal revelations of The Feminine Mystique”) to sexism in the theater, television, and film industries.

“It always comes out a little funnier than I think it’s going to be,” Rebeck says. “Somewhere in me, there’s somebody who’s got a gimlet eye about this stuff—it’s part of my machinery...but [the book has] got a good heart. It’s got a good, shrewd heart, I would say. And I think that people really are intrigued and curious and slightly terrified by what our culture cooks up, and that this has some thoughts around that, and also characters you can root for. We’re all looking for people who are trying to be heroic, whether or not they fail.”

Megan Labrise writes “Field Notes” and features for Kirkus Reviews.