Cinema: Also Showing - Girlfriend in a bobble hat

Stepmom (12) Two Girls and a Guy (15) Very Bad Things (18) A Man and a Woman (PG)

As titles go, Stepmom is particularly dithering. The poster's saggy too - Susan Sarandon and Julia Roberts in bobble hats, under a watery sun. It's amazing how one word and two faces can unearth so much testiness. At my local Tube station, people keep colouring in Roberts's eyes and giving Sarandon incipient acne with Biros. Bravo. In the film, Sarandon plays the ex-wife, Roberts the live-in girlfriend, and Ed Harris the chap. Sarandon and Harris have two adoring children who hate Roberts, the unreliable usurper. She's a photographer with very good skin. For the first half of the film, Sarandon and Roberts stand in kitchens putting each other down and flouncing off to sit, mute and regretful, in those enormous family jeeps. Harris isn't given very much to do, but sometimes looks sad that his children are chock-a-block with a registry of hurts.

For the second half of the film, Sarandon is diagnosed with cancer, and everybody decides to get along. Harris still isn't given very much to do, except snog Roberts like he can't believe his luck whenever she's not tending the sick. Sometimes Harris goes out for dinner with Sarandon. These are Hollywood dinners - the kind where everybody orders whisky and then leaves in a hurry without eating even a salad. One day Sarandon decides she likes Roberts, offers her children to the stepmom, and puts on that bobble hat.

This is a film about decent people doing the decent thing (meanwhile, the audience, refreshingly made up of people who have no problem whatsoever with being difficult, sit there thinking, "Somebody punch somebody"). It's a film about a woman who lives for other people and who wears the requisite hunted expression. If this woman wasn't Sarandon, then Stepmom would be altogether hopeless. But with eyes like two huge, sun-bleached Maltesers, Sarandon looks very clever - like she might be secretly translating everything you've just said into Latin.

Two Girls and a Guy stars Robert Downey Jnr as a slippery performance artist with two girlfriends (Heather Graham, Natasha Gregson Wagner). One day he returns to his New York loft and is confronted with the facts: the girls have found out all about each other, they have broken in, and they are furious. James Toback's film might work better as a play - it all happens in one room and the cast of three do lots of intimate, confrontational, London Fringe kind of raging.

This film was made in the 11 days before Downey returned to prison for drug offences, and is full of a windy melancholy. There's lots of yelling and flushed faces, but it's really more about longing than bickering, about how we can use relationships as a surgical glove, barely there but protective, scared that once it gets removed we might be revealed as docile and featureless. Tobak is fascinated with Downey, and spends most of the time following him about, like someone with a crush. So we get to see a little too much of Downey phoning his mother, or doing a bad Hamlet, or playing the piano, or wandering about barefoot and looking pinched and daring.

In Very Bad Things Christian Slater oversees Jon Favreau's stag night in Las Vegas. One of the party of five drunken men accidentally kills a prostitute, and then Slater murders a snooping security guard. They all agree to chop up and bury the bodies (very Shallow Grave) and return home stunned.

Very Bad Things might have been ferocious and successful if it hadn't tried to be two films - the other starring Cameron Diaz as the lunatic bride-to-be. It's as though director and writer Peter Berg couldn't face following through what he suggests in the early moments of the film. Sometimes, Very Bad Things is like the viciously brilliant In the Company of Men, which was also about men posing and dictating while secretly feeling like holes in the air. The Neanderthal shriek in both of these films is directed at life, but born from work. In both, we see men in offices like boys at boarding school, and marriage is spied as just another tourniquet. Underneath all the silliness in Very Bad Things is a faint voice talking about men going about the business of destruction in between faxing and arranging seating plans. It could have been a waywardly glossy portrait of institutionalised man.

Claude Lelouch's A Man and a Woman is rereleased this week, almost 32 years ago to the day from when it first opened in the West End. Jean-Louis Trintignant plays a racing driver falling in unlikely love with a widow (Anouk Aimee) to an incessant theme tune that always reminds me of the sound of rain on a plastic anorak (dabba-dabba-da). Aimee and Trintignant do particularly great Hair, a dense, unfuzzy gloss on top and eyelashes so long that when they kiss, they almost lock.

Watching A Man and a Woman is like being inside the pages of a Sixties copy of Vogue. The pair smile the smiles of people who drive with the roof down, laughing in fitted tweed on their way to a weekend with a groovy baron in Le Touquet. It's all very privileged and shiny. What has kept the film fun is not the giddy cinematic trickery (sepia, then colour, then black and white), but the spark between the two leads, who emerged from it as international stars. A well-behaved film that not only offers real warmth, but is sure to ride any January fatigue with a snug smile.