When a film’s pillow talk includes such gems as “kids are like rats, they carry disease,” it’s a good indication that there will be some trouble with the romantic part of the romantic comedy. Julie Delpy’s new film “2 Days in Paris,” which won an enthusiastic reception at this year’s Tribeca Film Festival and begins its theatrical run today, uses an unsentimental approach to pave new and humorous roads to romantic comedy. The French actress, best known for her cherubic face and wispy blond locks, has had to wait a long time to direct a feature-length film, and the wait has paid off.

Ms. Delpy, whose acting career began at 14 with a role in Jean Luc-Godard’s film “Detective,” is best known stateside for her work with Richard Linklater and Ethan Hawke in the chance encounter films “Before Sunrise” and “Before Sunset.”

“2 Days in Paris” has more than a little in common with Ms. Delpy’s “Before” films, but it has less to do with the kismet romanticism of an American’s fantasy of a European trip than the real-life difficulties of navigating a relationship in a foreign country.

The film follows Marion (Ms. Delpy) and her American boyfriend Jack (Adam Goldberg), a couple whose romantic trip to Venice gave way to dysentery and a stalled sex life. On their way back to New York, they stop in Paris for two days to pick up Marion’s cat and see her family. Their subsequent encounters with Marion’s strange but loving family (with the role of her parents and cat played by Ms. Delpy’s real life parents and cat) and her strange but numerable ex-boyfriends lead to cracks in what had seemed like a stable two-year relationship.

Ms. Delpy’s film trades on some of the usual foibles of an American abroad but resists making all of the jokes at Mr. Goldberg’s expense. The director clearly has a deep affection for both her adoptive and native lands and lovingly mocks them both. Jack only speaks English and insists on taking photographs of everything that he encounters, but his tattoos and dark complexion bring out a racist streak in some of the people the pair encounters; the Parisians, from Marion’s ex-boyfriends to her father and mother (Albert Delpy and Marie Pillet) are sex obsessed.

Similarly, Marion is not immune to mockery. Though her backstory as a photographer with a visual affliction borders the melodramatic, her neuroses and anger issues are intricately drawn. It is refreshing to see a female lead with quirks that run the risk of veering closer to repulsion than charm. Marion may be beautiful, but she is a strange little bird, and the film is not afraid to posit that she might not be worth all the trouble.

Mr. Goldberg, frequently relegated to minor slacker or chirping best-friend onscreen, takes well to the role of paramour. His character is compiled of odd juxtapositions that he handles with ease. Though Jack is often caught up in his own minor travesties, Mr. Golberg’s easy mannerisms make him a sympathetic and appealing character.

And watching him interact with the French language is a terrific aspect of the film. The addition of a language barrier to the battle of the sexes adds a great dynamic. Marion is not a trustworthy narrator, and Jack often finds himself adrift in the conversation. Left to deduce what his girlfriend is discussing with her friends, family, and strangers, he sits uncomprehending. Jack shifts from prostrating himself to responding with jealousy and rage as he tries to piece together the conversation from gestures and tone of voice. Inevitably, he thinks the conversation is all about him. Some of it is. Some of it might be worse than he suspects. Most of it is better.

Similarly, Jack is confronted with how little he actually knows his girlfriend. Marion is not entirely up front about her family, her homeland, or her past lovers, for reasons that are not immediately clear. But the divide between the couple’s nationalities, sexes, and temperaments all lead to surprising moments of humor and pathos.

Drawn together by their dark humor and hang-ups, Marion and Jack find out a lot about their incompatibilities in this unusual setting. Clearly, the pressures of travel have changed the dynamic of their relationship for what seems like the worse.

Sometimes, trying to romanticize life in an ideal setting forces everything apart, and Ms. Delpy has positioned this relationship breakdown well against the backdrop of an idyllic Paris. At one point Jack exclaims: “We’re not in Paris! We’re in Hell!” With Paris’s cafés, winding streets, and gardens exhibited at their most beautiful, Ms. Delpy sets the deterioration of Marion and Jack’s relationship in high relief.

Any director who tracks a relationship with a loving portrait of a city will get compared with Woody Allen, but here, Ms. Delpy inadvertently makes herself look like him as well. Behind thick black frames, with her wild blond curls, Marion is as neurotic and funny as Mr. Allen at his best. In fact, if Mr. Allen were one of the impossibly beautiful women with whom he is always setting himself up onscreen, his films might look more like “2 Days in Paris.”