The film adaptation of Jandy Nelson’s YA novel “The Sky is Everywhere” skips along the thin line between “wears you down” and “wears you out.”

A tale of teen love and grief with a heaping helping of magical realism, it’s a mostly-engaging if often cutesy portrait of processing the loss of a beloved sibling, and needing to “fall into the arms” of someone just to escape it.

Grace Kaufman of TV’s “Man with a Plan” stars as Lennie, our heroine, leading lady and (almost incessant) narrator, a teen growing up with her Earth Mama granny (Cherry Jones) and pothead uncle (Jason Segel), struggling with realizing that “the most terrible thing can happen at any time.”

That was the sudden loss of her vibrant, outgoing and artsy sister Bailey (Havana Rose Liu) to the same health condition that took their mother.

Lennie must soldier on alone, taking a lot of time off from school to walk the woods of California’s “Enchanted Forest” (Eureka, California was the filming location), looking for “signs” beneath the Candelabra Redwoods and calling her dead sister’s voice mail to leave messages about what she’s feeling.

Lennie is virginal and obsessed with “Wuthering Heights” and its tale of love denied and deferred, and she’s “lost the one person on Earth who understood me.”

Returning to school isn’t a big help, even with Honor Band class, bubbly BFF Sarah (Ji-young Yoo) and cute bandmate Joe (Jacques Colimon) suddenly showing a little interest in her. That Juilliard dream she shared with her sister is gone, and Lennie’s prone to self-destructively lashing out. Mean girl and first-chair clarinet competitor Rachel (Julia Schlaepfer) is ready and willing to exploit that.

Perhaps the only person to share her grief at Lennie’s level is Bailey’s beau, landscaper Toby (Pico Alexander). But maybe he’s not the right person to turn to for comfort.

Lennie’s life, at this moment, is a riot of sensations, processing and hormones. And hanging out with two aging hippies with their magical roses, symbolic houseplant named Lennie (it’s dying) and offers of “a session in the Truth Mobile,” talking about one’s feelings in her mother’s old minivan, may not be the path to mental health this kid sorely needs.

Impulsively bad choices, curling up in her sister’s closet and abandoning her “dream” and much of what makes Lennie herself might be her journey, or could turn out to be her destination.

Director Josephine Decker (“Madeline’s Madeline”) helps author and screenwriter Nelson realize her vision for this adaptation. That includes lots of sister flashbacks, an exultant memorial service that didn’t quite satisfy Lennie’s needs and plenty of special effects and other visual whimsies.

Rose bushes turn into humans who embrace Lennie when she listens to Bach with fellow musician Joe. A piece he plays on the trumpet literally bowls over their classmates as they’re walking down a hall. And when Lennie recalls Bailey’s way of “moving through the world like music,” it becomes a delightful street dance scene.

Lennie’s roiled emotions and hormones are played-up in a somewhat realistic way how someone too young to know how to act might react to grief. But it plays as shallow, and when she narrates “Grief is a house that disappears each time someone knocks at the door,” one hears the author’s own voice grasping for faux profundities.

That said, the hard-won courtship between “grief girl” and music boy is sweet, and the on-the-nose casting of the adults, Jones and Segel, pays off exactly as one would hope.

And our child-actress-turned-young adult girl-next-door lead makes this flawed heroine sympathetic enough that she wears you down even as the movie around her sometimes just wears you out.

Rating: PG-13 for language, sexual references and drug use

Cast: Grace Kaufman, Jacques Colimon, Havana Rose Liu, Pico Alexander, Cherry Jones and Jason Segel.

Credits: Directed by Josephine Decker, scripted by Jandy Nelson, based on her novel. An A24/Apple release.

Running time: 1:44