“Petit Mal” is the ever-so-precious title of a minor Spanish melodrama about three twentysomething women who try a “throuple,” a lesbian menage a trois, on for size.

Director, writer and co-star Ruth Caudeli has crafted an intimate, quiet, self-consciously arty and petit prétentieux/petit terne (dull) film about what happens when that peaceful, work-in-progress relationship is tested by a long separation.

Marti, short for Martina (Silvia Varón), Anto (Ana María Otálora) and Laia (Caudeli) share a house, a pack of five dogs and their lives together in a kind of “unequal” romantic/domestic relationship.

They may lightly tease about which two aren’t allowed to speak Catalan instead of Castilian Spanish in front of the other and who “always burns the vegetables” when they’re cooking paella. But they eat off the same paella pan and seem to love and support one another in an almost conventionally unconventional way.

And when Laia talks about how penguins “mate for life,” we are allowed to guess where the fissures will open, because plainly she is the glue that holds the trio together.

Laia has some undefined job in film production which calls her to LA. Is she supporting them? Marti is editing a documentary about their lives together. And emotional Anto is a musician who sits at the piano at one weepy point and composes a lament, “One of three, and I’m alooooone” (in Spanish with English subtitles).

Laia’s leaving leads to tearful “Miss you” Facetime and creates quite the strain at home, where Marti and Anto apparently never would have gotten together were it not for Laia’s butch dyed-blonde allure. Something has to give. What will it be?

Caudeli doesn’t give us a movie of shouting matches, but of subtle, almost silent longing and loneliness. The women back in Spain take some time to get into sync, and find that one thing they might bond over is mutual suspicions of what that female tomcat Laia is up to it LA.

Even that isn’t debated out loud.

Caudeli leaves out back story altogether and takes a very long time to identify every character by name, which is naturalistic (most intimates don’t feel the need to call those their lover anything other than “Amor.” The writer-director never quite reveals exactly how these three keep home and hearth together, although we see one person stuck doing the dishes, another trusted with most of the cooking.

Instead of “how does this work” logistics, Caudeli lets us figure that out without all the information we need. We just observe.

She does that irritating, self-conscious filmmaker thing of serving up this scanty story in titled “chapters,” including “2: We convulsed.” That’s what “Petit Mal” means, a “tiny seizure.” Here, that’s the shock of separation and what it produces.

Every shot, including the right-on-cue sex scene, is beautifully-composed, with the middle acts filmed in black and white to show the color that’s drained out of the relationship that Laia appears to have masterminded.

It’s not a badly-crafted film, just a shallow gloss on these characters and a relationship that they don’t explain, don’t dissect and analyze, but simply live.

That’s not enough.

Rating: unrated, sex and nudity

Cast: Silvia Varón, Ana María Otálora, and Ruth Caudeli

Credits: Scripted and directed by Ruth Caudeli. A Dark Star release.

Running time: 1:29