Ross and Rachel (Assembly George Square, Edinburgh)

Ross and Rachel. Rachel and Ross. Except it's not Rachel and Ross. It's always Ross and Rachel. "I don't know when people started saying our names together," says Molly Vevers. She doesn't mind too much – "but why does his always come first?"

Ross and Rachel. Ross and Rachel. You know the ones. On-again. Off-again. On-again. Off-again. On a break. On again. Them. Vevers plays them both, though they're never explicitly named, flicking between them without so much as a flicker.

James Fritz's play picks up the relationship where Friends left off, that happy ending. Ross at the wrong airport. Rachel's "I got off the plane." It's like fanfic gone sour.

Why did we think that they'd last? Why, after all they went through – all those 'on a breaks' and those other marriages – did we ever imagine that that was happily ever after?

This is The One with the Brain Tumour. It's The One with the grinding dead-end marriage; The One where they stay together for the Kids. It's The One when Rachel sees Ross for what he really is: a pathetic, possessive control freak and misogynist fantasist. It's The One that rubbishes the very idea of The One; The One that proves real life is not a sitcom; The One that makes you swear to carpe that diem for all that you're worth.

If the liberal sprinkling of pop culture makes this piquant, the gender politics and wasted lives give it plenty of real-world clout. She's been cowed into this marriage by social pressure: too scared to stay single, but now too late to leave. He, meanwhile, seems completely deluded: wrongly convinced that real men date pretty women, regardless of everything else. He's fixated. She settled. She settled for him, for what he wanted – for what he thought he wanted. It's heartbreaking: a relationship that should not have been resuscitated. How, you think, had we not seen it before?

Our familiarity allows Fritz free reign and some of his writing is just level-up stuff: pained, resentful, resigned; a neat blend of cynicism, whimsy and sincerity. Ross imagines life after he's gone, as his memory melts into 'first husband' status and he becomes a footnote at her funeral. Rachel sucks in her every explosive thought, trapped by his tumour into a role she never really wanted: devoted wife and dead weight. That's Friends ruined, then.

Ross and Rachel is at Assembly George Square Theatre until 31 August