Of all the praise lavished on Sally Rooney’s first novel, Conversations with Friends – that it was glittering, witty, addictive, elegant, heartbreaking – only the insistence that it was especially contemporary, and “could sit with Lena Dunham’s Girls”, as the Sunday Times put it, didn’t seem entirely applicable. True, the author was only 26; yes, the story took place in an Ireland where Catholicism no longer mattered, and everyone was a digital native; and the narrator, Frances, was a new graduate who started the book in a modishly fluid friendship/relationship with the avowedly lesbian and definitely woke Bobbi. But the instant messages were used to produce something like Platonic dialogues; email functioned, like Victorian letters, to consider the workings of the heart; time was marked by the publishing of novels and the passage of the seasons rather than the irruptions of news; and Frances was not only diagnosed with endometriosis without ever googling Lena Dunham but very soon abandoned her never specified relationship with Bobbi for an all-absorbing affair with an older married man, Nick.

The resulting doomed romance appeared closer to Rosamond Lehmann’s novel The Weather in the Streets (1936) or Barbara Trapido’s Brother of the More Famous Jack (1982) than to chilly contemporary autofiction or modish surrealism. There was the scant plot of these earlier classics, the romanticised, aphorising characters, the shamelessly beautiful sentences and exquisite, precisely considered suffering. There was even the calamitous female physicality, with Frances’s bloody struggles with endometriosis reminiscent of Lehmann’s portrayal of abortion or Trapido’s of birth; and, underneath the relentless irony of the dialogue, Frances’s haunting innocence and yearning, her distinctly pre-feminist sense of a lack of entitlement to love, which is perhaps much more like Lehmann’s Invitation to the Waltz than Girls. Above, all there was an engaged, questing subjectivity and an underlying faith in fiction itself, which seemed modernist rather than contemporary. Frances’s pain and striving are leading us somewhere: Frances is discovering her singular self and becoming a writer – and this, Rooney’s passionate creation tells us, is worthwhile.

Normal People, written in barely a year since that debut, is set mainly in the same shadowy, smoky, studenty Dublin, has the same witty dialogue and delicately observed play of often anxious feeling, and the same interludes of startlingly graphic, passionately intimate sex. It, too, is astonishingly fresh: in fact, when these books are shelved together in the future, it may seem that Normal People is the earlier work. It’s a slightly smaller book, for a start. Conversations with Friends at least aspired to be a quadrille, including Bobbi and Nick’s formidable wife Melissa in the dance, along with memorable turns from Frances’s troubled parents. Normal People, by contrast, is a waltz, or possibly a tango, with two protagonists only: Marianne, a skinny, anxious, clever girl, like Frances but with even less self-esteem and more masochistic tendencies, who begins the book as a social outcast reading Swann’s Way in the school lunch hall in Galway, and Connell, the apparently secure and popular working-class star of the football team.

Sally Rooney’s first novel, Conversations with Friends, was a doomed romance.

Sally Rooney’s first novel,
Conversations with Friends, was a doomed romance. Photograph: Patrick Bolger for the Guardian

The spotlight is the brighter on these two because everyone else is just a little darker and more blurred than in Conversations with Friends. The couple’s friends are not only more distant than Bobbi, but more cliched, absorbed in teenage intrigues about dances, committees and a slightly disconnected subplot with a death and funeral that recall Heathers or The Big Chill rather than life or books. The villains of the story are well drawn and thoroughly contemporary – the boyfriend with the sly taste for porn; the sexist bully in a nightclub; an artist who exploits young women on the internet – but they also each disappear within a chapter or two, either without action from the protagonists, or even, in the case of the sinister artist, on request.

Their families, too, have taken a step towards the vague and gothic. Connell’s mother Lorraine comes, we are told, from a criminal family and had him at 17: but this does not seem to have left her with any unsatisfied adult desires or even awkward acquaintances. Rather, she is consistently kind, selfless and wise, the “good mother” counterpart to Marianne’s widowed parent, who is cold, neglectful and encourages her brother’s violent bullying. But Denise is so vaguely drawn, it seems even Marianne cannot be bothered to explain why. After an outrageous cruelty on her part, the two mothers and Marianne directly encounter each other:

They saw Marianne’s mother in the supermarket. She was wearing a dark suit with a yellow silk blouse. She always looked so ‘put together’. Lorraine said hello politely and Denise just walked past, not speaking, eyes ahead. No one knew what she believed her grievance was.

Even the differences of class and social ease between Connell and Marianne seem to dissolve as the book progresses. Connell goes to Trinity College Dublin alongside Marianne, who is now a social swan, and he never thinks of football again.

The energy and excitement of the story, then, must come from the couple themselves, their inner lives, what they see and imagine and read; from what Jane Austen called their “sensibilities”. Fortunately, they have a lot of these, and Rooney evokes them superbly. Connell turns out to be quite a lot like Frances, too, and it is he, not Marianne, who is to be the writer. He may be defensive about this:

It feels intellectually unserious to concern himself with fictional people marrying each other. But there it is: literature moves him. One of his professors calls it the pleasure of being touched by great art.

And, whatever the reality or otherwise of the dangers around them, however many times they have absurd quarrels or, conversely, seem to meld and share an identity, that pleasure, of being touched by great art, is to be had in reading the story of Connell and Marianne, just because Rooney is such a gifted, brave, adventurous writer, so exceptionally good at observing the lies people tell themselves on the deepest level, in noting how much we forgive, and above all in portraying love. She shows the way it works on the skin – “The intensity of the privacy between them is very severe, pressing in on him with an almost physical pressure on his face and body” – and the mind:

He and Marianne are like figure-skaters, improvising their discussions so adeptly and in such perfect synchronisation that it surprises them both.

Connell leaves the library “in a state of strange emotional agitation” when he has to break off from reading Jane Austen’s Emma, and we feel the same way when he fails to explain properly to Marianne why he needs to spend the summer elsewhere, or when Marianne involves herself with a man she does not even like. Connell does not look up the ending of Emma on his phone, as surely most young people would, or even make a quip about the film Clueless, and we don’t want him to, because his mind is more exciting than that.

Normal People may not be about being young right now, but better than that, it shows what it is to be young and in love at any time. It may not be absolutely contemporary, but it is a future classic.

Kate Clanchy’s The Not-Dead and the Saved is published by Picador. Normal People is published by Faber. To order a copy for £9.99 (RRP £14.99) go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99.