Starring Jason Segel and Emily Blunt. Rated 14A. Now playing

Overlong, overwrought, and underthought, The Five-Year Engagement might be better if it knew what it was about. Cowritten by star Jason Segel and director Nicholas Trotter and produced by Judd Apatow (whose previous collaborations include Get Him to the Greek and Forgetting Sarah Marshall), the two-hour-plus romcom mashes sweetness and vulgarity into an ultimately indigestible stew.

This gastronomic notion fits with the potty-mouthed movie’s odd difficulty in conveying what makes Segel’s character, Tom Solomon, one of the best effing chefs in San Francisco. His occupation remains a somewhat arbitrarily chosen impediment to the career advancement of his fiancée, Violet, played with slumming charm by Emily Blunt. When she gets into a psych-department grad program at the University of Michigan in snowy Ann Arbor, it turns out to be the one place where Tom can’t find suitable work.

Violet flourishes in the new gig, which puts her, ahem, under a mildly dashing Welsh professor (Rhys Ifans, who has somehow morphed into leading-man material). Meanwhile, our galumphing hero loses his way, as does the movie, when a local faculty husband (Chris Parnell) gets him obsessed with hunting. Jokes about crossbows and venison pie have about as much relevance as Ted Nugent records, but they do show the big dude’s growing disconnect with his sleek partner, and they keep putting off the wedding.

Seriously, though, what’s the big deal? The movie isn’t about a long engagement; it’s about two people who, you know, live together for roughly five years, with doubts occasionally getting the best of them. How unusual! The couple’s problems grow tedious, and all those Van Morrison songs don’t help. More fun is had by the supporting players, with Parks and Recreation’s Chris Pratt and Mad Men’s Alison Brie standing out as Tom’s dimwitted best bud and Violet’s wacky Brit sister. These two marry and reproduce almost as soon as they meet, and we thank them for being succinct.

Watch the trailer for The Five-Year Engagement.