Let us raise a toast to Jason Segel. First he did his bit to banish the post-Christmas fug with his script for, and starring role in, 2012's sweetest movie, The Muppets. Now he's given anyone in need of a post-Euro 2012 pick-me-up plenty of laughs with The Five-Year-Engagement, a perfectly cast rom-com that, like The Muppets, shows Segel's range as a writer and actor is wider than many have given him credit for.

He's joined here by off-screen pal (it shows in the chemistry) Emily Blunt for a story all about hitches before getting hitched and the trauma that people put themselves through when they lose sight of the fact that the big day is about them and not, well, all the other stuff. Someone you know, and possibly love, is in this movie somewhere.

San Francisco chef Tom (Segel) proposes to academic Violet (Blunt) on New Year's Eve, a year to the night after they first met. No sooner is the ring on her finger than Violet is offered a great university job - in Michigan. The happy couple put the wedding plans on the long finger and Tom decides to go Midwest with Violet, only to discover that his boss wanted him to run her new restaurant when he hands in his notice.

Tom buries the disappointment, but not too deep, and it's not long before cracks begin to appear in his relationship with Violet. He can only get a job in a sandwich bar and meets the 'widower' of another academic, who now spends his time knitting and hunting as he supports his wife's career. Violet, meanwhile, falls under the spell of her smarmy boss Winton (Ifans) and begins to resent what she perceives as Tom's lack of ambition. Nevermind walking down the aisle, will they even see another New Year's in together?

Why do people who love each other end up putting each other through the ringer? That's the question that's constantly in your mind while watching The Five Year-Engagement, and Segel and director/co-writer Stoller's depiction of relationships, successes and disappointment has that lived-in/through feel. "A bit of Irish stoicism never hurt anyone," says Tom as he faces into a Michigan winter. Millions of us would, however, disagree and Segel shows his acting muscles as his character bottles up his hurt and confusion as he struggles with his loss of identity. After this, the serious roles only seem a matter of time.

That's the heavy stuff, but in between there are quality gags that involve past lovers, crossbows, frostbite, food-themed eroticism and impersonating Sesame Street characters while discussing what went wrong between man and woman. From the ever-dependable Blunt to co-stars Brie and Pratt, Segel and Stoller spread the good gags around, with the message about not getting hung up on perfection coming through loud and clear. And how's this for a line to remember next time you're dealing with matters of the heart? "Underneath all that polite b*******," opines Ifans, "we're all running on caveman software." There's more where that came from, too.

At a little over two hours, The Five-Year Engagement rambles a bit, but you may feel that this is part of its charm. These characters are special, and it would be great to see them in 10 years' time in a Before Sunset-like sequel. Until then, a bit of never-gets-old advice: a wise soul once said that the key to a great relationship was to never go to sleep angry with your other half. After a night out at this, the chances of that happening are remote.

Harry Guerin