"One Day" diversifies itself from your standard romantic story about the prolonged consummation of two longtime friends' love for each other by playing out on the same date over a roughly twenty-year period. By providing a mere snapshot of these people and how their lives metamorphose in the span of two decades, director Lone Scherfig (2009's "An Education") and writer David Nicholls (adapting from his best-selling novel) create a microcosm for life itself in all its various transmutations, pitfalls, achievements, disappointments, and unforeseen forks in the road. If the soulful connection between them isn't always bought into or as sweepingly amorous as it ought to be, chalk it up as more proof that there is enough substance and care to the rest of the film's ideas and themes for it to hardly matter.

They meet July 15, 1988 on the morning after their graduation from Edinburgh University, sleep together without actually sleeping together, and then share a wonderful few hours before heading in separate directions. Working-class Emma Morley (Anne Hathaway) wants to change the world, a talented writer with plenty of big dreams but no immediate means of getting ahead. Handsome, womanizing Dexter Mayhew (Jim Sturgess) comes from a well-to-do family and is on a faster track toward fame and money. They share little in common, but a tight, caring, albeit tempestuous, bond forms immediately. Through ruts and successes, significant others and break-ups, professional high points and meltdowns, Emma's and Dex's relationship threatens to rip apart as the distance between their values grows vaster. The spark of who they are inside and what initially drew them to one another, however, suggests there may still be hope for a future as a couple after all. They'd better hurry, though; time does have a way of sneaking up on a person.

Were the love story between Emma and Dex in "One Day" more distinct and tangible, who knows how high it could have risen in the annals of the genre. As is, it might be the weakest element in an otherwise perceptive drama about the passage of time and the universal struggle to make something of a life that is going by more quickly than we'd like. The relationship between Dex and Emma never quite feels right, perhaps because the film's particular narrative device requires that the days and years go by quickly without a huge amount of development. Emma, who has loved Dex since the first day they met and even wrote poems about him in her journal, gradually divorces herself from the dream of being with him as she sees how different they are. If she is thoughtful and idealistic at the onset, the years of slaving away at dead-end jobs turn her into a realist. As time often does, Emma's troubles work themselves out and she finds joy in teaching—if not so much in her sparkless romance with struggling comedian Ian (Rafe Spall). Dex, meanwhile, is noncommittal and stuck to the fake happiness of materialism. Through hosting gigs on bad television programs, alcohol and drug abuse, his mother's (Patricia Clarkson) battle with cancer, a serious relationship with Sylvie (Romola Garai), and a wake-up call that's been a long time coming, Dex grows up. It just takes much longer than it should have, and soon he's a has-been pushing forty who must start over in figuring out what he wants to do with the rest of his life.

Director Lone Scherfig wants to make the point that Emma is the road Dex should have taken all along, so it's too bad the film doesn't quite sell this sentiment. Anne Hathaway (2010's "Love and Other Drugs"), speaking with a flawless British accent, and Jim Sturgess (2008's "21"), speaking in his native tongue, are exceptional guides for this particular story, aging subtly but surely over twenty years from fresh-faced collegiates to more world-weary adults approaching middle age. Hathaway and Sturgess are both likable—and in the latter's case, this is difficult to manage with such a flawed character as Dex—and their individual tales grab one's sympathies. There are oddly missing character details—Emma's parents, mentioned only once and never seen, are a non-entity throughout, and her triumph of getting her first novel published happens maddeningly off-screen when it should have been front and center—but these oversights are exceptions rather than rules. What is lacking is the feeling that Emma and Dex deserve no one but each other, a hard pill to swallow after a heartbreaking scene where a coke-addled Dex cruelly tells teacher Emma, "Those who can, do. And those who can't..." Hathaway's reaction to hearing this is the picture's best moment. Also lingering long after the moment has passed is Patricia Clarkson's (2010's "Cairo Time") touching admittance that she worries her son isn't the nice person he used to be. For Dex, that's the worst thing he could hear, but the meaning of her words don't hit him until years later.

There's never enough time. Doesn't that always seem to be the case? What "One Day" lacks in palpable romantic chemistry between Anne Hathaway and Jim Sturgess, both actors make up for it with their own personal effervescence. As Dex and Emma seek to find their way through their respective lives, where they end up seems to be fated. The ending, not immediately predictable until it's approaching, is bittersweet and unfair, but honest because of it. Audiences not familiar with the novel will be divided, but "One Day" stays true to itself and the people it follows. Without knowing what's around the next corner, Emma and Dex must press forward with all the uncertainties of the world still up in the air. They, like everything else, will one day not be there.