As a beleaguered cartoonist whose wife leaves him on their twin daughters’ fifth birthday, Jemaine Clement cautions a student not to pity him. “It’s fine,” he says. “I’m just having a bad . . . life. It’ll be over eventually.”

Clement, who perfected dry dialogue in HBO’s “Flight of the Conchords,” is dejection perfection as the cuckold whose wife (Stephanie Allynne) leaves him for a “monologuist” (Michael Chernus). Is that a thing? “According to the MacArthur Foundation, that’s a thing,” notes Clement’s character, Will.

She and her new beau exemplify the combination of overreaching creativity, narcissism and childishness that collectively equal the condition known as “Brooklyn.” Will, whose love for his girls is adorable, tries to maintain a link with his ex: “We’re more than friends. We’re parents.” Meanwhile, he tiptoes into a possibly healthier relationship with an emotionally fragile Columbia professor (Regina Hall).

Filled with arch wit, the film is sweet and sorrowful at the same time. Like many indies, it lacks much of a conclusion, though writer-director James C. Strouse shows that simple ideas, ably executed, can make an endearing film.