Writer-director Gary David Goldberg is best known for his work in television sitcoms, and in “Must Love Dogs” he certainly doesn’t stray far from his roots. Within the first ten minutes of the movie he’s incorporated an astounding number of tube cliches. First there’s the fundamental premise of a recently-divorced woman who’s gorgeous but nonetheless can’t seem to find a man. Then she turns out to be a pre-school teacher, so that he can introduce a passel of precocious kids. And she’s got a large, colorful family, including not only a recently-widowed dad who will inevitably take up with a brassy woman his daughters won’t initially like, but one of those annoyingly intrusive sisters who will take it upon herself to post ads for our heroine on an internet dating service. Need more? There’s the inevitable gay best friend. And the montage of dead-end first dates. And the ultra-cute naughtiness (especially in a sequence where our girl and her guy desperately try to find a drugstore that stocks condoms before taking to bed). Want cute musical bits? There are several–the worst being a sudden outbreak of “The Partridge Family” theme song. (Even the number has to have a sitcom connection, it seems.) And the title insures scads of canine reaction shots to ooh and ah over. (John Bailey’s cinematography, which gives the images a glassy, plastic appearance, makes the picture look like a sitcom, too.)

In the midst of all this, of course, is the obligatory romance. Through the agency of that meddling sister (Elizabeth Perkins, who fails to make the character the lovable buttinski she’s meant to be), Sarah Nolan (Diane Lane, looking a trifle washed-out under Goldberg’s flaccid direction) meets–cutely, of course–the recently-divorced Jake Anderson (John Cusack), a quirkily charming boat-builder who’s obviously perfect for her. But in the fashion of such stories, they’re kept apart for ninety minutes or so by a string of interruptions, misunderstandings and instances of self-doubt, the most notable involving another potential suitor for Sarah, Bobby Connor (Delmot Mulroney, playing the thankless part decently enough), the recently-separated father of one of her students, who turns out to be–could you not have guessed?–a ladies’ man. Acting as a kind of counterpoint to the Sarah-Jake story is the dalliance of her father Bill (Christopher Plummer, predictably smooth) with a lively trailer-park resident named Dolly (Stockard Channing, predictably sassy). It’s quite appropriate that Bill, patriarch of the big Irish clan, speaks with a slight Celtic accent (as also does Craig Armstrong’s background score), because everything that happens in “Must Love Dogs” is the purest blarney. (Also sitcom-strength dream. Sarah might be but a pre-school teacher, but she seems to have no money problems maintaining her big old house, and Jake has an equally sumptuous place, despite the fact that we’re repeatedly told he’s never managed to sell a single one of his hand-crafted wooden hulls.) That’s particularly the case with the big finale, in which Goldberg reaches way too far to devise an extra-adorable way for Sarah and Jake to overcome the final obstacles keeping them apart–resorting to a coincidence even more implausible than the rest of the plot.

In fact, about the only reason to sit through “Must Love Dogs” is Cusack. Though he looks a bit tired here (even compared to his work in such equally lightweight pieces as “America’s Sweethearts” and “Serendipity”) and the lines provided him by Goldberg have nowhere near the verve of the dialogue he’s enjoyed in his best films, he’s still by far the nimblest part of this ensemble, even making the gag devised to prove Jake’s sensitivity–his devotion to “Doctor Zhivago”–seem less awful than it actually is. One other cast member makes an impression: Jordana Spiro as Sherry, the dumb, promiscuous blonde Jake links up with after he and Sarah temporarily part ways. She comes on too strong, but if anybody ever does a film biography of Goldie Hawn, she’s the actress to cast. The resemblance is striking.

But overall “Must Love Dogs” is a romantic comedy that barely meets the standards for network renewal, which nowadays are gruesomely low. If you love this movie, you’re figuratively obeying the title’s injunction.