Teens with cystic fibrosis find love — at a distance

It isn’t actually adapted from a Young Adult novel, but “Five Feet Apart” definitely has the mood of the more serious offerings from that literary shelf.

And like “The Fault in Our Stars,” this film deals with teenagers who are sick. So sick that 95 percent of the story takes place inside a hospital.

For most of the film, this limitation is no problem; what we see is funny and well-acted. Then — well, we’ll get to that.

In the opening scene we meet Stella (Haley Lu Richardson), who’s back in the hospital for her umpteenth visit. She lives with cystic fibrosis, the illness that produces an overabundance of mucus in the body.

Occupying the room next door is her childhood pal Poe (funny Moises Arias, from “The Kings of Summer”). As fellow “C-effers,” they know the ups and downs of the condition.

The new kid in the hospital block is Will (Cole Sprouse, who plays Jughead on “Riverdale”). He’s skeptical about his new treatment, and likes to talk about the inevitability of death.

Will is tall, handsome and brooding; Stella is short, pretty and upbeat. How long will it take for these two to put aside their differences and get together?

But the almost surreally sad reality, as the script by Mikki Daughtry and Tobias Iaconis goes to great lengths to explain, is that people with CF (at least these two people) dare not get into close proximity. If they touch, they might exchange the wrong kind of bacteria and become mortally sick.

This means Stella and Will can’t hold hands, let alone kiss. Director Justin Baldoni makes good use of the widescreen frame, keeping these two on separate sides of the screen, so we never forget the physical gulf between them.

It’s a poignant situation, and the film’s rough-edged, unsentimental attitude prevents the material from getting cloying or clinical — the kids have been sick so long they’ve developed shared jokes to keep pity at bay. The hospital wing becomes a world unto itself, where the young patients create their own special community.

Haley Lu Richardson, from “Edge of Seventeen” and “Support the Girls,” gives a rich performance — she creates an authentic, deglamorized human being. But not a saint: Stella has her own pushy personality, which includes her need to control everybody else’s treatment.

Having built this scenario, “Five Feet Apart” goes seriously wrong in its final act, ginning up melodrama and having the characters do dumb things to further the plot. It’s a shame — the very specific characters we’ve come to know deserve better.