Three lives at humorously operatic pitch

Bisexuality certainly increases the geometric possibilities of the romantic comedy, completing its triangles and allowing for quadrangles and other, more amorphous layers of amorous involvement.

The primary vertex of “Puccini for Beginners,” writer-director Maria Maggenti’s pleasant comedic romp, is Allegra, an opera-loving writer played by Elizabeth Reaser. A self-proclaiming lesbian (or so she keeps saying), Allegra short-circuits her nine-month relationship with Samantha (Julianne Nicholson) by allowing her intellect to trump her passion, thus driving Samantha back to a prior boyfriend.

This triggers a screwball-inspired series of happily accepted implausible coincidences that find Allegra impulsively falling into simultaneous affairs with Philip (Justin Kirk), an assistant philosophy professor at Columbia, and his soon-to-be ex, Grace (Gretchen Mol), an investment banker who’d rather be a glassblower. Allegra, still reeling from being dumped by Samantha, is further flummoxed by the fact that she is sleeping with a man, not to mention her inability to bypass cute, ostensibly straight girls who throw themselves at her.

However unlikely her new bedmates might be, Philip’s tweedy, bespectacled academic and Grace’s ditzy but sensible blond offer Allegra two archetypes from classic romantic comedy she just can’t resist. Naturally, none of the three is the least bit aware of the others’ involvement with one another.

The setting is contemporary Manhattan -- nicely shot by cinematographer Mauricio Rubinstein -- but one that would be easily recognizable from Woody Allen movies of decades past. The characters congregate in second-hand bookstores, neighborhood restaurants, revival houses and Lincoln Plaza, and there’s almost something nostalgic about the way they inhabit the city. They’re the types of self-conscious movie intellectuals who use big words and quote Freud, Emily Dickinson and feminist critics but are otherwise as inept at navigating the dating gantlet as the rest of us.

Maggenti (“The Incredibly True Adventure of Two Girls in Love”) keys off Allegra’s fondness for opera by structuring her film with a prologue and epilogue sandwiched around three acts. But whatever pretensions exist in the script, Maggenti winks at them knowingly. Though the dialogue may not quite have the crackle and pop necessary to completely pull this off, it nevertheless is more sophisticated than most of what passes for relationship comedy these days.

The filmmaker’s niftiest trick is in making a group of neurotic, self-involved, overly verbal people so engaging. But then, you have to like a movie in which nerdy (albeit attractive) characters couple and uncouple with the profligacy of rabbits as they learn to navigate the territory that lies between the heart and the mind.

kevin.crust@latimes.com

“Puccini for Beginners,” unrated. Running time: 1 hour, 22 minutes. Exclusively at Laemmle’s Sunset 5, 8000 Sunset Blvd., West Hollywood, (323) 848-3500; Laemmle’s One Colorado, 42 Miller Alley (inside plaza), Pasadena, (626) 744-1224; and the Edwards Westpark 8, 3755 Alton Parkway, Irvine, (949) 622-8609.