Many of the most scarring breakups we suffer in life are not with lovers, but with friends: people we once trusted with our most closely guarded truths, reduced over the years to strangers, or more wrenchingly still, to polite occasional acquaintances. Yet we rarely refer to these breakups as such. We talk about “drifting apart” or “losing touch” or some other euphemism that makes the loss sound less severe, as if our friendships carry less weight than our romances. We belittle them, even, with phrases like “just friends,” as if the designation is somehow less complex. The unstinting marital drama is a genre unto itself; rarer are the films that scrutinize the progression of a platonic friendship with equivalent gravity and intricacy.

“You’re kind of an odd couple,” a mutual college acquaintance observes of Mara (Tallie Medel, also Sallitt’s lead in “The Unspeakable Act”) and Jo (Norma Kuhling), not masking his surprise that their friendship has endured into full-blown adulthood. On the surface, you see what he means, beginning with the visual contrast between Mara — diminutive, dark-bobbed and stern-faced — and willowy, wavy-haired boho blonde Jo. One is grounded and sensible, the other impulsive and unreliable: You’ll guess which is which. Yet it doesn’t take long to see the shared vulnerabilities and protective instincts that bind them, which has extended into their mutually care-based professions: Mara is a kindergarten teacher and Jo a social worker, though the former holds down her job rather more solidly, as the latter is unmoored by bouts of mental illness.