Bromance, as it’s now called, isn’t really new to movies, but from the way John Hamburg deals with it in “I Love You, Man,” you’d think that male friendships were so unusual that a comedy about one would be mind-blowing. It isn’t, especially since it spends a full 104 minutes on an idea so artificial that it could have been handled in a sitcom in 22—and a mediocre sitcom at that.

The notion is that Peter Klaven (Paul Rudd), an amiable real-estate guy just engaged to Zooey (Rashida Jones), doesn’t have a single close buddy he can ask to be his best man. (The explanation is that he’s always been such a lady’s man that he’s never had time for male pals.) When his fiancee’s chick friends and his own family needle him about it, he decides to get such a buddy immediately, and after some awkward set-ups arranged by his gay brother Robbie (Andy Samberg), locks onto Sydney Fife (Jason Segel), a big, blustery fellow he meets at a showing of Lou Ferigno’s house (cue the cameo) who’s a real man’s man (and happens to share Peter’s tastes in music and stuff like that). Unfortunately they hit it off so well—and Sydney is such a boor—that their relationship ultimately threatens the wedding.

This is all very peculiar. It’s hard to know what to make of Peter, who on the one hand is supposed to be a chick magnet but on the other is kind of prissy (it’s understandable that some of his “dates” take him to be gay). The character is well suited to Rudd, though, since most of the humor is verbal, involving him stumbling over what he’s trying to say before stammering something embarrassing out, and he manages it very well. A pity that the gag is amusing enough for the first twenty minutes or so, but grows tiresome over feature length. It’s also hard to see where his problem lies once you learn that he has a brother with whom he seems to get along perfectly well and is an obvious best man (nicely played by Samberg, whose laid-back performance gives the picture a gentle charm whenever he’s around).

That adjective could never be applied to Segel, who’s as broad and vulgar as Samberg is restrained. It’s he, of course, who supplies the quotient of coarse, crude humor that’s obligatory in the Age of Apatow, and he has a few genuinely funny moments (I especially liked one of the quieter ones, when he unconvincingly asks a female golf partner who’s just hit him with a ball not to leave the green). But a little of his bulldog manner goes a long way, and when the predictable happens toward the close and he’s revealed as lonely and vulnerable, it’s very hard to stomach.

As to the rest of the cast, Jon Favreau is irritatingly thuggish as the unpleasant husband of Zooey’s friend Denise (Jaime Pressly, too flamboyant), and J.K. Simmons seems to be in Jonah Jameson mode as Peter’s loud father. (By contrast, all one can think about when watching Jane Curtin as his mother is how old she looks.) As for Jones, she’s okay without being especially engaging. And Ferrigno gets some easy laughs with his ungainly non-acting.

Technically “I Love You, Man” is good enough without being outstanding. Lawrence Sher’s lensing is fine, and Andrew Laws’s design and Eric Sundahl’s art direction are solid, but the picture isn’t visually distinguished. Nor does Theodore Shapiro’s score add any sonic distinction to dialogue that hasn’t sufficient verbal fire.

If you’d like to see a premise along these lines handled with wit and finesse, rather than the blunderbuss approach taken here, try Patrice Leconte’s delicious French dramedy “My Best Friend” from 2007, with Daniel Auteuil and Dany Boon. Of course, you’ll need to read subtitles. But it’s worth the effort.