Scenes from a Marriage, B2, Belgrade, Coventry<br />Land of the Dead/ Helter Skelter, Bush, London

Love lies crushed in the wreckage as couples crash

Trevor Nunn has sent himself to Coventry along with his wife Imogen Stubbs and Iain Glen. I should hastily explain, this isn't a gossip column and no pouting celebrity bust-up has occurred. We're talking amiably supportive regional gig here. The Belgrade Theatre recently emerged from a major architectural overhaul with a promising new 300-seat studio named B2.

Sir Trevor began his career at the Belgrade in the 1960s, and now his big-name staging of Ingmar Bergman's Scenes from a Marriage is providing a boost for the venue's fresh start. Nunn's star actor is also the brother of Hamish Glen, the artistic director who is determined to bring modern European classics to Warwickshire. I regret to say all this does not make the evening unmissable.

Certainly, Bergman's play (adapted from the 1973 Swedish TV serial which he also re-edited for the big screen) is strewn with probing tragicomic moments about the slippery nature of love and long-term relationships. Initially, Marianne (Stubbs) and Johan (Iain G) seem the perfect couple, still faithfully devoted on their 10th anniversary. However, a chink of ambivalence appears when she suddenly asks if he has ever thought of sleeping with anyone else. Later, he initiates an uncomfortable conversation about waning sexual interest. "I do my best," she says, wincing. There is, furthermore, an abortion (which is not in the cinema version), multiple affairs and a messy separation where neither can stop being drawn back.

Everyone who has been through the mill will flinch with recognition at the bruising realities exposed. This play is a variation on Ibsen's A Doll's House (with both spouses feeling stifled and the man walking out). At the same time, you can feel the live current of Bergman's autobiographical experience feeding into the action – and, boy, he knew the terrain. He was married five times.

Nonetheless, the really sharp flashes of pain and humour are somewhat few and far between in this staging. Glen's Johan turns startlingly callous, with a sense of vigorous release from being Mr Nice Guy, and Stubbs conveys staggered distress. Yet the acting isn't quite as scintillating, close up, as you might expect from this company. Stubbs's emoting feels slightly self-conscious, and one wonders if it mightn't be a tad inhibiting being directed by your own husband.

Joanna Murray-Smith's English adaptation is more obviously to blame, leaving some lines sounding like stiff translations. The many scene changes, with much furniture shifting, are a hitch too, although they are smoothed over by mildly touching home movies flickering on the back wall – glimpses of the couple playing with their children.

As for the current fad for video-projected scene headings, why does an audience ploddingly have to be told whenever a day, a month or a year has passed? It would be far more dramatically unnerving simply to be plunged back into the story, further down the line, feeling the lurch of a revelation and thinking, along with the characters, "Christ, how did we come to this?"

At the Bush, a new pair of short plays by Neil LaBute – snapshots of two wrecked relationships – prove riveting. These are directed by Patricia Benecke, who is definitely a name to watch. Land of the Dead is a kind of scarred memorial to one morning in New York. An aggrieved woman (Ruth Gemmell) and her insensitive partner (John Kirk) step into two pools of light and speak to us, but not to each other. Kirk is a superficially brash, bantering City trader who has hurried off to have breakfast with his boss before happily ensconcing himself in his skyscraper office. She is more palpably shaky, left to make her own way to an abortion clinic only to find, on her return, a faintly repentant voicemail from him saying that maybe she shouldn't go through with it.

The added tragic twist, making her grief infinitely more complex, is that this particular morning is 9/11. Benecke conveys this fact with a roar of a plane cutting between a couple of speeches. The simplicity is electrifying, paired with subtly nuanced pin-sharp performances. Helter Skelter, in which a pregnant wife discovers her husband's casual adultery, has an over-inflated ending with allusions to Medea. The restaurant setting doesn't add much either. But Gemmell is again mesmerising and LaBute brilliantly captures how rage blasts a rational conversation into shards.

That said, anger can be powerfully articulate. In response to the Arts Council's seriously miscalculated plan to cut the Bush's funding by 40 per cent, the foyer walls are covered in eloquent graffiti. Here are blazing statements from British playwrights and directors, all recognising the invaluable contribution that this talent-nurturing theatre for new writing has made to our culture.

'Scenes from a Marriage' (024-7655 3055) to 2 February; 'Land of the Dead'/ 'Helter Skelter' (020-7610 4224) to 16 February