For those familiar with his work, the title of David Ireland's new play, written during his tenure as writer-in-residence at the Lyric Theatre, is something of a double-edged sword, referencing not only its central theme of an irresistible - if unlikely - love affair but also the unforgettable content of what has gone before. Ireland, who trained as an actor - and notched up some impressive credits early in his stage career - has amassed a rapidly-growing canon of work since his first play What the Animals Say was produced just four years ago.

But for all his verbal fluency, his tangential imagination and clear understanding of dramatic form and structure, his tendency towards writing relentlessly explicit scenes of sexual violence has provoked audience reaction ranging from hysteria to queasiness and downright disgust. He is capable of displaying copious helpings of irony and audacious humour, as in Yes So I Said Yes, the surreal comedy premiered by Ransom at the 2011 Belfast Festival, which caused frissons of disapproval when it toured regional venues. On the other hand, he can be deadly serious, as demonstrated in Half a Glass of Water, developed and produced in 2011 as part of the Abbey Theatre’s annual short play reading series and performed by Field Day at the end of 2012. The jury is still out on this disturbing double-hander, which saw Stephen Rea as a convicted rapist locked in a chilling encounter with his deeply troubled young victim, played by Conor McNeill.

It is impossible to discard these nagging memories when approaching his latest piece. Based on previous experience, one could have no expectation of an evening of wine and roses. But Ireland is nothing if not a surprising writer and here, in the deft hands of first-time director Conleth Hill, he springs his biggest surprise to date.

The Lyric has placed on the piece an 18+ rating, impishly warning of "scenes of a sexual nature, bad language - and some Ulster Scots". That three-pronged promise is honoured in spadefuls, gleefully wrapped around a Graduate-inspired love story between a young politics graduate and a Glaswegian widow and directed by Hill with all the mischievous attention to detail he brings to his own performances.

When Stevie and Martha meet in a coffee shop over two books and a cappucino, little do they think that the ensuing romp in Martha's bedroom will amount to anything more binding than the occasional bout of casual sex. After all, Martha is 49 and still recovering from the death of her husband, seven years previously. She has uprooted to Belfast simply because she is due a change of scenery and feels at home there. In Karen Dunbar's skilfully-crafted, multi-faceted performance, it is not long before Martha's outwardly confident, brazen exterior falls away to reveal a desperate, needy, middle-aged woman, struggling to walk the line between the demands of her youthful lover and the predictable disapproval of his mother, who is but a year older than herself.

Broth-of-a-boy Stevie is on the rebound after being dumped by his girlfriend Ciara, labelled by his über-Christian sister Rebecca as dirty and faithless. "Are you a Catholic?" she asks, surveying with distaste his squalid bedsit. "No!" he replies. "Then why are you living like one?" she returns, prompting the first of many outbursts of loud laughter. This glinting, knowing tone effectively punctuates the evening, producing sharply nuanced, instantly recognisable characterisations. That is to say, instantly recognisable in the North. For if this piece has a difficulty, it is in the fact that it is hard to imagine it travelling very far, so rooted is it in the layered complexities of David Ireland's own home patch.

Cultural stereotypes abound, delivered with cavalier self-awareness and performed with tremendous assurance. How, for example, to unpick the dogged insistence of Carol Moore's brilliantly realised Dorothy - Stevie's mother - that she comes from Sandy Row, in spite of having lived off the Newtownards Road for the past goodness knows how many years? Both are working class, staunchly loyalist areas on opposite sides of the city, but there is, nevertheless, is a world of difference between them, as arguably only a local audience would fully realise and relish.

Abigail McGibbon's Rebecca is Ulster Protestant to the core, though with a few little concealed flaws here and there. God-fearing and righteous she may be, but she is not averse to a few too many glasses of red wine nor to slagging off her ex-husband in the strongest possible terms. She and her mother live together in an uneasy alliance, which extends to them heading off to church together every Sunday and taking a holiday in Disney World, with her five-year old son, the gloriously named Paisley.

Returning from Florida, with Dorothy resplendent in a Minnie Mouse hairband and Rebecca in a Daffy Duck baseball cap, they spy through the window Stevie and Martha locked in a bout of excruciatingly embarrassing sexual activity. For what seems like an eternity, the two remain rooted to the spot, their faces frozen in expressions of utter repulsion. It is a bold feat of directing and acting, particularly as the howls of laughter from the audience rise in volume. And the comedy doesn't end there. The appalling spectacle they have witnessed sparks not only a kind of moral paralysis in Dorothy but an impassioned ode to the joys of oral sex from a clearly envious Rebecca, while Declan Rodgers's swaggering Stevie is reduced to a writhing, mortified wreck.

Ticking the boxes at the interval, one realises that the aforementioned scenes of a sexual nature and bad language have materialised in no small measure. But Ulster Scots? It is early on in the second act that McGibbon cranks up her class act another notch. Warming to Martha after discovering that she is a Protestant from Glasgow - "... the motherland!" - she unleashes the full welly of the Ulster vernacular upon her, to the renewed delight of the audience, the mystification of Martha and the derision of Dorothy, who demands that she stops speaking in "... that silly voice ... you sound like a drunken farmer from Ballymena."

A slightly duff note sounds late in proceedings through the intervention of Stevie's ex, Ciara. Her arrival presents Naomi Rocke with the thankless task of portraying a half-formed character, who registers as little more than an excuse for a spot of sectarian cat-fighting.

Complemented by slick lighting changes by James McFetridge, Stuart Marshall's set design uses only minimal switches of colour and soft furnishings to move the action between Stevie's bachelor pad, Martha's rented apartment and Dorothy and Rebecca's neat-as-a-pin home. Within these defined spaces, tangled attitudes and conflicting relationships unwind to a harmonious conclusion, allowing each character his or her dignity and offering the opportunity for love to flourish in this previously cold climate.

Jane Coyle is a Belfast-based freelance arts journalist and critic, who also contributes to The Irish Times, The Stage, Culture Northern Ireland and BBC Radio Ulster.