From left, Charlie Day, Jason Sudeikis, Justin Long and Drew Barrymore in a scene from the romantic comedy Going the Distance. (Jessica Miglio/Warner Bros. Pictures)

In a summer full of frustrating and muddled rom-coms, Going the Distance just might be the most frustrating and muddled of them all. The film has plenty going for it – Drew Barrymore, for one thing, and a surprisingly authentic premise. I kept rooting for it long after it self-destructed, sensing there was a better movie trapped inside that was dying to bust out.

Barrymore and Long are both real and likable throughout, but they are forced to work with material that’s beneath their abilities.

Going the Distance’s early scenes have a messy charm about them. If the slackers from Reality Bites turned up on the dating scene 10 years later, this could be their movie. Commitment-phobic N.Y. record company peon Garrett (Justin Long) meets 31-year-old newspaper intern Erin (Drew Barrymore) at a bar, and after bonding over lots of beer and a few games of Centipede, they decide to go home together.

Garrett and Erin’s hookup is treated with refreshing frankness. This isn’t love at first sight for either of them, just a fun night spent getting tipsy and messing around. Erin is headed back to Stanford in six weeks and she’s upfront about her attempts to make a swift exit in the morning. But Garrett is charming enough to buy her breakfast, and as the two chat and joke about their shared interests and the shaky industries they’ve both entered, they fall into an easy patter that suggests there’s romantic potential in this fling.

Helmed by Nanette Burnstein, whose background is in documentaries, Going the Distance approaches something like realism in its first third, when the couple’s courtship is documented with handheld camera and shot in decidedly un-romantic natural light. During an early date, Erin bombards Garrett with all sorts of getting-to-know-you questions, and as she hits him with gems like, “How would you like to die?” Barrymore’s delivery is so fresh and believable it feels like she’s improvising.

The two are so great together that when Erin is due back at school out west, viewers will be right on board with the couple’s decision to give the long-distance thing a try. Their vow to keep things “disease-free and light” sounds pretty sensible, and one wishes Burnstein and screenwriter Geoff LaTulippe could have put half as much thought into their depiction of the ensuing relationship.

Going the Distance starts to flatline the minute Erin leaves New York. Cutesy attempts are made to bridge the gap between the lovers at first. Burnstein fills the frame with split-screen phone calls, text messages and those little cartoon airplane-journey maps left over from Sleepless in Seattle. But nothing can disguise the fact that Erin and Garrett are more fun together than apart, and while Barrymore is snappy enough to carry scenes alone, Long suffers when he’s not acting across from her. He’s actually quite funny – never more so than in a brave bit alone in a tanning booth – but mostly, the script calls for him to make hangdog faces via Skype, and earnestness is not the actor’s strong suit.

Justin Long, left, and Drew Barrymore hit it off in Going the Distance. (Jessica Miglio/Warner Bros. Pictures)

Once things start floundering, Going the Distance summons up some of the most cardboard, unlikable supporting characters imaginable to fill dead air. There’s Erin’s overprotective, nagging sister, Corinne (Christina Applegate), who deserves a special spot in the rom-com shrews hall of fame. Then there are Garrett’s guy friends, Box (Jason Sudeikis) and Dan (Charlie Day), who exchange endless banter about everything from Burt Reynolds’s moustache to masturbation.

There’s a lot of crass talk in Going the Distance, with the men and women alike riffing on everything from oral sex to dry humping, and dropping F-bombs almost every minute. The idea of an R-rated rom-com that actually dares to acknowledge that its characters swear and have sex is welcome, but the thoughtless manner in which these gags are staged smacks of a desperate attempt to appear edgy.

In the midst of all of this cacophony, Erin and Garrett’s more serious relationship drama is almost lost, and Burnstein’s laboured attempts to carry the couple through a number of by-the-book conflicts late in the movie feels like an afterthought.

There is a better movie trapped in here somewhere, one that actually cares about two young lovers attempting to juggle uncertain careers and a relationship worth fighting for. Barrymore and Long are both real and likable throughout, but they are forced to work with material that’s beneath their abilities — like a dumb, uncomfortable scene of unsatisfying phone sex. In that low moment, it’s painfully clear that this lifeless film was doomed from the start.

Going the Distance opens Sept. 3.

Lee Ferguson writes about the arts for CBC News.