When Nicholas Stoller and Jason Segel introduced “Forgetting Sarah Marshall” in 2008 it represented the low point for the Apatow factory, during the phase when it produced any old comedy premise that could fit on the back of a bank receipt. The filmmakers probably didn’t go in thinking, “we’re going to make a stalker fantasy laughfest,” but that’s what came out the other side.

That’s why it’s so encouraging to see the same group produce “The Five-Year Engagement,” easily the most balanced of the Apatow battle-of-the-sexes comedies. The fairer sex does not get off the hook, but a stronger female side creates a sharper give-and-take between man and woman. This advantage is heightened by casting one of the most gifted comedic stars of her generation, Emily Blunt, rather than the hot T.V. star of the moment.

The result is a comedy with compelling and real characters that feels like it comes from someplace true rather than wild exaggeration. When the film finally ends in a wacky Hollywood fantasy wedding, it feels less like a cynical conclusion than a bit of earned whimsy, like the end of a Fellini film (no, it’s not that good).

The gags relate to the difficulties of engagement, particularly one that lasts forever, and the winter blues of Ann Arbor, Michigan. Tom and Violet (Segel, and Blunt) meet in San Francisco, fall in love and get engaged there and end up moving to A-Squared when she gets a post-doctorate assignment. The couple delays marriage again and again. Her academic career thrives under a zap-haired professor. He gives up his chance to be a great chef, grows a Grizzly Adams beard, takes up crossbow hunting, and sinks into misery (while some critics have griped about the Grizzly Adams phase being too far afield, you can be assured that Tom is not the first person to grow a beard in Ann Arbor.)

While many of the criticisms directed at the film (too long, weird digressions, tone shifts from reality to exaggeration) are not without merit, “The Five-Year Engagement” earns clemency by coming from a real place and being consistently smart and funny. While some of the comedy set-ups are unoriginal lifts from other films, it doesn’t feel that way, because there’s a plausible relationship with real chemistry underlying it.

The “Five-Year Engagement” profits from that relationship between Segel and Blunt, who share a loose, playful chemistry. They seem remarkably at ease. They’re matched nicely by her sister and his best friend, Allison Brie and Chris Pratt, respectively, who relive the plot of “Knocked Up” as a counterweight. They are the couple forced into a marriage by pregnancy. They make it work despite the difficulty of the situation solely because they want it to.

That’s why “The Five-Year Engagement” sees the Apatow romantic comedy finally getting into the ballpark of the thirties films that they always seem to aim for but usually fall short of. It works as comedy, or romance. Or both, in fact. What are you waiting for? Go.

[Read more reviews by Kevin Bowen]