“The Last Five Years” sings the love story of Jamie Wallerstein, a promising young novelist in New York City, and Cathy Hiatt, an aspiring actress. Adapted from Jason Robert Brown’s stage musical, the movie’s scenes are almost exclusively sung by its principal characters.

The high-concept storytelling in “The Last Five Years” doesn’t stop with the singing. Cathy’s songs begin at the end of the couple’s marriage and move backward to the beginning of the relationship. Jamie’s songs begin at the exuberant start of the relationship and move forward to its grievous end.

The unconventional chronology makes the tale all the more poignant. A creeping sense of loss, juxtaposed alongside the happiness in the relationship that’s told in reverse from Cathy’s perspective, runs through it all.

Being warned about the film’s high concept storytelling doesn’t necessarily make it easy to follow. It’s probably best to go with the flow and not dwell on the chronology.

Writer-director Richard LaGravenese (“Behind the Candelabra,” “The Fisher King,” “The Bridges of Madison County”) helms “The Last Five Years” and its impassioned performances by principal cast members Anna Kendrick and Jeremy Jordan.

Kendrick, of course, is the major star in this small yet fairly expansive adaptation. An actress and a singer who previously appeared in the far bigger-budgeted hits “Pitch Perfect” and “Into the Woods,” she gives “Last Five Years” all the joy and sorrow she’s got.

Jordan, Kendrick’s co-star, is less well-known than she, but, with his Broadway experience and TV and film musical roles, he dives into the part of Jamie, giving an outsized performance that fits the Jamie character perfectly.

“The Last Five Years” has a realistic, if not new, story. Jamie springs from a well-to-do Jewish family. Success is expected of him. And he’s supposed to marry the “right” girl from the “right” family. That means Jewish. Cathy, however, comes from a working-class, non-Jewish family in a modest New Jersey town from which she was desperate to escape.

Jamie’s opening song is all about his head-over-heels love for Cathy. The fact that his family will disapprove of a shiksa girlfriend thrills him all the more.

“You are the story I should write, I have to write!” he proclaims. “I’m your Hebrew slave!”

Kendrick’s and Jordan’s emotional journey through courtship and marriage coupled with Brown’s storytelling are the movie’s big draws. The musical side of the film, however, is its weakness.

Brown’s songs and instrumental score swing from Stephen Sondheim-style tunelessness to pop, rock opera and neo-classical chamber music. There’s not one memorable melody in the entire pastiche.

In the end, which is, inevitably, heartbreaking, Kendrick’s and Jordan’s bursting-to-wilting performances are worth the 90 minutes invested in this swiftly moving, set-to-music anatomy of a marriage.