Forever Yours, Mary-Lou (Ustinov Studio)

Around the stage, tiny figurines sit side by side, staring out at the world with a smile. His arm reaches gently round her back. Her head rests on his shoulder. They are the very definition of young love. Over time, however, sweethearts can turn sour.

Michel Tremblay's four-hander catches a marriage gone stale – not quite in its death throes but not far off either. Airlifted from Quebec to Ireland by translator Michael West, swapping the original joual – a working-class French Canadian dialect – for the local lingo, it puts a warring family onstage, each in a separate spotlight.

Liam and Mary-Lou are at loggerheads, bickering over the groceries – crunchy peanut butter and the like – but with a wellspring of resentment in reserve. He's a horrorshow of a husband: the sort who rules his family home like a fiefdom. Their two teenage daughters, Carmen and Mandy, are listening in behind the door, terrified and transfixed – but they're also remembering the argument ten years later, long after their parents' death. Tremblay fizzes back and forth, rewiring the dialogue so that three separate conversations seem like a circuit.

Tremblay writes a beautiful argument, one that ebbs and flows like a symphony. It's almost flirtatious at times, tart and playful, as if forged out of fondness rather than frustration, but when it wants to be, it's as bruising as a thumb forced into flesh.

Your first instinct is to abhor Liam, the bullying breadwinner who insists 'his house, his rules.' Paul Loughran plays him like a medieval monarch – the sort with drumstick in hand. In time, however, you pity him. Tremblay very subtly adjusts the focus, pulls back from these private lives to admit the wider social situation – his 20-odd years in a low-paid, menial job, operating the same machine day-in, day-out until "you know it like your first fucking girlfriend." What does that do to a body? To a brain? To a man's sense of self? "I'm already half fucking robot," he harrumphs.

There's little respite at home, only a wife, hiding behind religion, terrified of sex. You can't blame her either – not with a boor of a husband, who first slept with her skunk-drunk and stinking. Caitriona Ni Mhurchu turns her back, all sadness and sang-froid. They've had sex four times in 20 years – all rape, she says – and they've four children to show for it. Each moment of intimacy plunges the family further into financial crisis – more bills, more beds. It's a cycle so vicious it kills them.

The kids are less clear – though you can clearly see the impact of their upbringing. Amy McAllister's Mandy, cross-eyed like her father's side of the family, has turned to religion; Carmen (Caoilfhionn Dunne), the spit of her mother, to sex and country singing. Laurence Boswell's pared back production, played face-front, glitches with repressed trauma and Isobel Waller-Bridge's superlative sound design fuses together the sounds of young romance and old rancour. The arguments still ringing in the two daughters' ears likely mean they'll never enjoy that statuesque version of love – arm in arm, side by side.

Forever Yours, Marie-Lou (A Toi, Pour Toujours, Ta Marie-Lou) runs at The Theatre Royal Bath until 30 April.