The Prudes, Royal Court, London, review: Anthony Neilson trains a rare spotlight on the wilted libido in this funny, frank, and sad piece

The subject of sexual impotence does not often rear its head on our stages. But Anthony Neilson trains a rare spotlight on the wilted libido in this funny, frank, playful and sad 75-minute piece which he has written and directed.

Long-term couple Jimmy and Jess used to have a satisfying sex life. They drew the line at the harder stuff like dogging (“We don't have a car for one thing,” explains Jess) but their repertoire was quite adventurous. The problem is that they have not had intercourse – she's noted it in her diary – for 14 months and four days.

Tonight, though, is make or break time. They are proposing to reboot their relationship while we watch, here and now. The studio theatre has been transformed into sugary pink mocked-up boudoir of swagged sheets, lacy curtains, and shagpile carpet (the ace design is by Fly Davis).

R Kelly's “Bump n' Grind” on the sound system is not exactly urging restraint. So no pressure then. The couple sit on stools at one end and sip wine to steady their nerves. The atmosphere is like some bizarre game show rather than anything more tumescent.

Neilson's achievement is to take the proceedings into some dark and uncomfortable places in ways that don't rip right through the texture of comic absurdity created by the format. Jonjo O'Neill and Sophie Russell – who have great rapport as actors and bond with the audience brilliantly – treat us to the intimate secrets of the characters' enforced celibacy: the pervasive sense of shame; the guilty bouts of solitary masturbation (“we wank alone”); his joyless immersion in porn, “trying to find little spikes of truth”.

The piece is very funny and shrewd about how Jimmy uses his supposed feminism as a strategy for not facing up to his erectile issues and trying to make love again to his wife. “No one hates patriarchy more than me!”, he exclaims.

But it's all about him, not her. After discovering something horrible about Jess's early sexual experiences, Jimmy has withdrawn into the bunker of his brain – “it's like I've taken on her trauma instead” – and become so woke as to be useless.

O'Neill is hilarious: his character in a self-dramatising lather of worry over, say, the college girlfriend whom he now thinks he did not give enough time to emerge from sleep before they had sex. Did she consent, or just relent. “I don't know what's allowed any more”.

Sophie Russell's Jess is wised up to his ways with a wry exasperation and is latterly more assertive. “You don't want me not to be me?” she asks, when it emerges that he has brought along a couple of costumes for her that might get him going.

Reluctantly getting dressed up as Wonder Woman seems to release the fury in her, though. It's an open-ended piece that concludes not with a climax but a small gesture of love and the sound of Streisand ablaze with the song “He Touched Me.” A tentative fresh start, perhaps.

Until 2 June (royalcourttheatre.com)