You can dismiss it as the young adult version of a Nicholas Sparks story, or as an Afterschool Special on steroids, but there can be little doubt that John Green’s YA novel “The Fault in Our Stars” touched a nerve among a large segment of the teen female demographic, and it’s probable that its phenomenal success will carry over to Josh Boone’s screen adaptation. “The Fault in Our Stars” is unquestionably a sappy, manipulative movie, but on those admittedly low terms it succeeds.

The central character is Hazel Grace Lancaster (Shailene Woodley), a sixteen-year old afflicted with cancer. Though an experimental treatment saved her from death some time before and she remains in remission, there’s no assurance about how long she’ll survive, and in any event she has to constantly lug an oxygen tank around with her to help her breathe.

Concerned that Hazel’s too solitary—especially since she spends so much time endlessly reading her favorite book, “An Imperial Affliction” by the recluse Peter Van Houten, which is of course about cancer—her attentive parents Frannie (Laura Dern) and Michael (Sam Trammell) persuade her to attend a support group led at a local church by a well-intentioned but hopelessly square guy named Patrick (Mike Birbiglia). Hazel wants to flee, but her first session has the considerable benefit of introducing her to Augustus Waters (Ansel Elgort).

Gus—an engaging hunk who’s also a cancer survivor, having lost a leg to the disease but now cancer-free—is actually there to support his buddy Isaac (Nat Wolff), who’s scheduled for surgery that will leave him well but blind. But he’s immediately drawn to Hazel, and in fact pursues her. Before long they’re a couple—a happy circumstance that can’t be said of poor Isaac, whose beautiful girlfriend Monica (Emily Peachey) unceremoniously dumps him when the direness of his situation becomes clear.

There’s clearly a “Romeo and Juliet” quality to all this, except that the villain isn’t some family feud—both youngsters’ parents are quite supportive of their friendship—but the disease they’ve shared. Still, Hazel is definitely swept off her feet by Gus, whose gregariousness is infectious. But the two characters aren’t equally plausible. Both are literary constructs, of course, but the girl is the more convincing of the two. That’s not simply because Woodley plays her well, though she does; it’s because Gus comes across as more literary, in the sense of seeming less authentic. His endless ebullience is one thing, but his affectations—like constantly dragging on an unlit cigarette in order to defy the power of the illness it represents—feel more contrived than real, despite the fact that Elgort plays him perfectly well, making him a likable, if not completely believable, fellow.

The clearest proof of Gus’s devotion comes in his decision to use the foundation-financed “Wish” he’s saved from his cancer scare to arrange a trip by him and Hazel to Amsterdam, where he’s apparently arranged for her to have what’s she’s always wanted—the chance to talk with Van Houten about his book. There’s something a bit unseemly about this plot turn—it feels a little like Green is cheekily referring to his fans’ attitude toward him. But the episode is redeemed by two things. One is the location work in Amsterdam, which as shot by Ben Richardson is quite lovely. The other is the fact that the author turns out to be a drunken jerk, contemptuous of Hazel’s love of his book, and is played with wonderful cynicism by Willem Dafoe.

There is a drawback to the Amsterdam sequence, however, in the youngsters’ visit to the Anne Frank house—an episode that finally leads them to open up to one another. The juxtaposition of Anne’s suffering with theirs can easily make one a mite queasy. But apart from that, the movie quickly veers into tragic mode after the European trip. It’s been quite apparent since their first meeting, even to one who’s not read Green’s book, that the relationship is bound to end tearfully, with sequences of physical decline and death. The only question is which of the two will succumb, and when. Rest assured that Boone, the scripters and the actors craftily prolong the agony so as to extract maximum weeping from those prone to cry in response to tearjerkers. The more hardhearted will be less emotionally affected, and will be pleased to know that Dafoe reappears at the close, as brusque and cynical as ever. That mitigates the sappiness a bit.

But of course for most viewers Green’s calculated assault on the tear ducts will work, so the concession stand would be advised to stock up on boxes of tissues—they’ll probably prove a more profitable commodity than popcorn in this instance. Amid all the weeping, the adequate but hardly outstanding technical credits—Molly Hughes’ production design, Gregory Weimerskirch’s art direction, Merissa Lombardo’s set decoration and Mary Claire Hannan’s costumes—will pass by mostly unnoticed. So will Season Kent’s unremarkable score.

The Shakespearean connection of Green’s book, and this movie, extends, of course, beyond the “Romeo and Juliet” factor to the title, which plays with the Bard’s words to emphasize that in this case the tragedy arises not from personal failing but from fate. The flaws in the picture, on the other hand, are the result of its makers’ decisions. Happily, they’re not fatal.