Movies about young love are hard to pull off, and when they don't work, they can be cloying and obnoxious. Done right, though, there is something both lovely and piercing about them, and while I think "If I Stay" has to do a fair amount of juggling to get its premise to work, there is a cumulative power to it that I found undeniable and earned.

"Earned" is a big word for me in films like this. One of the biggest problems when you're making a film about love between people of any age is showing how love sparks between people and how it flourishes and doing it without giving in to short-cuts or cliche. How many times have you seen a supposed romance and the meeting is completely ridiculous? How many movies have you seen where you're supposed to just accept that characters have fallen in love because that's what the film needs them to do, not because of anything we see in the movie?

Based on a novel by Gayle Forman, "If I Stay" tells the story of Mia (Chloe Grace Moretz) and Adam (Jamie Blackley), who meet in high school and begin dating, and one of the strengths of the film is that if that as the entire story, it would still be well-told and strongly acted and engaging in its own right. Mia's studying to be a professional cellist, and she's been driven since she was a kid. It's pretty much her entire life. I've known kids like this, kids who were completely focused on the thing they love, and I like that the film doesn't treat Mia as a nerd or a geek or a loser because of this. She's just driven to the point of having blinders on for everything else, so when Adam walks into her life, she's unprepared for it. He's just as driven as she is, but in his case, it's rock stardom that he's focused on. Like Mia, Adam is very talented, but unlike her, he's very comfortable in his own skin. He's a little older, and when Mia first notices him, it's like he's already left high school behind. He's a senior, but he acts like none of that matters to him. Even having noticed him, Mia isn't going to do anything about it. Her whole life is about practice.

Then one day, Adam walks by the practice room where Mia's lost in her own work, and that glimpse is all it takes. He recognizes something in her, and honestly, that's a big enough seed for genuine love to take root. I may be a slow learner, but at 44, coming on the heels of the implosion of my marriage and fortunate enough to be in the early days of something new, it is apparent to me that one of the foundations you have to have with someone if love is going to work is a similar world-view. That may mean that you love the same things, or it may mean that you approach parenting the same way, or it may mean that you simply share a pessimism or an optimism about the world. Whatever the case, the more connected you are, the stronger that union's going to be, and Adam and Mia are both so devoted to music, both so aware of the sacrifice it takes to become great at something, that they are able to build their life together in a way that makes room for the two of them to also be individuals.

There is more to the movie, though, and that's where I think it's a little bit busy. Maybe fifteen minutes into the film, Mia and her family are in a car crash. Unsure what happened, Mia finds herself standing beside the car, freaking out. Even stranger, she watches as paramedics load her body into an ambulance. She realizes something's happened to her, but can't quite make sense of it. It quickly becomes apparent that Mia is hovering somewhere between life and death, and as doctors work on her and try to save her, Mia begins to move backwards through her life, examining it, trying to find an anchor to keep her tied to this world.

The rest of the film explores the way Mia and Adam eventually ended up estranged and whether or not they are going to get back together, while also drawing out some suspense about which of Mia's family members either did or didn't survive the crash as well. Because of the device, there's a fair amount of running around on Chloe's part, and there are points where it feels like the device starts to get in the way of the story being told. What ultimately makes it work is the chemistry, and not only between the two leads. I feel like one of the magic tricks of filmmaking is casting a family that feels like a real family, and "If I Stay" pulls that magic trick off with aplomb. Mia's parents, Denny (Joshua Leonard) and Kat (Mireille Enos) were young and wild when they met, and what Leonard and Enos do so well over the course of the film is chart the way parenthood tames them as a couple without them ever giving up the things that make them who they are. It's really lovely work, and there's one moment in particular that really got me. The two of them are listening to Mia obsessively practice the cello, and while some people might be driven insane by the repetition, the two of them seem blissed out by it, with Enos finally taking her husband by the hand and saying, almost in awe, "We made that." That feeling of parental pride and amazement is one of my favorite things about being a parent, and they nail that in this film.

Obviously, with this subject matter, "If I Stay" has some serious tear-jerking on its mind, and this is where we come back to that word I mentioned earlier. This film earns the emotions, and it feels honest as it grapples with the huge emotional complications between Mia and Adam. I always hate it when movies about love have to manufacture some misunderstanding between the couple in order to drive them apart before act three, especially if it involves cheating. Adam and Mia struggle to stay together, but not because of some artificial crisis. They're just pulled in different directions by their ambitions, and they end up facing decisions that many young couples have to deal with, and they do so in a way that feels like they genuinely love each other. I will confess that there is something unsettling about seeing Moretz playing love scenes in the film, but that's simply because I've been interviewing her several times a year now since 2008, and she's gone from being this self-possessed kid to being a sharp and lovely young adult in what feels like the flash of an eye. She is young enough here that it feels authentic that she would be so nervous about intimacy, and it's handled with real delicacy. I'd compare the performance she gives here to Jennifer Grey's work in "Dirty Dancing" in terms of charting a realistic moment of awakening, and also in terms of showing real strength. She and Blackley are very good together, and he manages to play a convincing budding rock star without tipping over into being a cartoon and also without neutering the character. No easy feat.

There's also a scene late in the film involving Stacy Keach, who plays her grandfather, that positively destroyed me. I've always loved Keach as a tough guy icon, which makes it even more heartbreaking to see this man crumble as he says goodbye to his granddaughter. It reminds me of seeing James Garner break down in "The Notebook," and I think there's real power that comes from seeing someone who we're used to seeing play a certain kind of machismo suddenly break like this.

Director RJ Cutler, who started his career as a documentarian, does very good work with his cast, and the film is stylish, well-shot by John de Borman. Monique Prudhomme deserves praise for her costuming choices, particularly regarding Moretz. As I said, there are lots of scenes of her running around the hospital, and her costume seems to be have designed with that in mind. Shauna Cross' adaptation of the book is efficient and works hard to make the framing device feel organic. Her best work is in the scenes between Mia and Adam as they're dating, and if "If I Stay" has any real value, it is in showing a teenage relationship based on love and respect, with two people who treat each other well. I wish more love stories worked like that on film, because the ones that work in real life are certainly that way.

"If I Stay" opens in theaters this Friday.