Laura and Alec. Danny and Sandy. Harry and Sally. Ennis and Jack. What makes a great on-screen relationship? The simple answer is chemistry, that not at all simple blend of physical compatibility and complementary style, of sweet nothings and smart zingers, of ecstasy and agony, even of song and dance.

Some couples discover they have so much chemistry, they act opposite each other over and over again: Mr Tom Hanks and Ms Meg Ryan, Mr Adam Sandler and Ms Drew Barrymore, Mr Leonardo DiCaprio and Ms Kate Winslet, Mr Ryan Gosling and Ms Emma Stone. Filmmaker Mr Richard Linklater found the unlikely combination of Ms Julie Delpy and Mr Ethan Hawke so intoxicating he has returned to Jesse and Celine’s amorous adventures twice more since 1995’s Before Sunrise. When you find The One, or maybe The Two, you just know.

The five couples below are not necessarily the most romantic (that must be Rick and Ilsa in Casablanca), the most tragic (Jack and Rose in Titanic) or the most sharply funny (Harry and Sally) captured on screen, but they have one thing in common. They make you root for their relationship. So, when they finally get together, despite all the obstacles the screenwriters have strewn across their path, you find yourself punching the air.

Here it is, the film that gave the world Mr Ryan Gosling as romantic hero and in the process launched a million crushes and doe-eyed memes. In subsequent years, Mr Gosling has had his heart broken by a sex doll (Lars And The Real Girl), wordlessly seduced Ms Carey Mulligan in a lift (Drive) and tap-danced Ms Emma Stone into bed (La La Land). But this adaptation of Mr Nicholas Sparks’ soupy novel is the uber-Romantic Ryan. And in Ms Rachel McAdams, he finds his perfect, fiery foil. After a tense shoot – director Mr Nick Cassavetes revealed later that Mr Gosling had demanded a different lead actress – the pair dated for four years.

They play star-crossed lovers, Noah and Allie, in 1940s South Carolina. Allie is a little rich girl and Noah is from the wrong side of the tracks (Mr Sam Shepard plays his father, which tells you everything you need to know), or as Allie’s mother puts it, “He is trash! Trash! Trash! Not for you!” Snobbery, a war and a year’s worth of hidden letters conspire to keep them apart until, in a gloriously baroque plot twist, Allie spots a photograph in the newspaper. It is of the derelict house Noah has restored for her in exactly the way she dreamed – “a white house, with blue shutters, and a room overlooking the river so I can paint” – all those years ago.

The framing device set in a modern-day nursing home is syrupy enough to cause toothache, but as a portrait of puppyish young love growing into death-do-us-part companionship, it is, simply, weepy perfection.

The Wedding Singer is almost the perfect romantic comedy, packed with neon nostalgia, a brilliant 1980s soundtrack and a charming central couple who, crucially, make each other laugh. In 1998, both Mr Adam Sandler and Ms Drew Barrymore were at the peak of their careers and yet, as Julia and Robbie, they manage, effortlessly, to convince audiences that they are losers. Ms Barrymore’s cute-as-a-button waitress, soon to be Mrs Julia Guglia (a fact that Robbie does not allow to pass unridiculed), is riddled with a vulnerability that makes her stick with her unfaithful fiancé Glenn. Mr Sandler has a real darkness at his core as a jilted, failed rock star, and together, they sparkle.

The film climaxes not at the airport, as is traditional in rom-coms, but in the air, with an extended Mr Billy Idol cameo and Robbie’s song, “I Wanna Grow Old With You”, playing over the loudspeaker. In the closing scene, Julia and Robbie’s wedding day, Mr Steve Buscemi sings Spandau Ballet’s “True” – the definition of couple goals.

In recent years, there has been no more tender, erotic rendering of the pangs of first love than in Mr Luca Guadagnino’s Call Me By Your Name. Set in a rambling villa in northern Italy – a lust-worthy object in itself – it stars Mr Timothée Chalamet and Mr Armie Hammer as teenager Elio and graduate student Oliver, who embark on a short affair that lasts only as long as the six-week summer holiday, but burns all the more brightly for that.

The film’s mood is sun-dappled lunches beneath the trees and languid dancing under the stars, baggy holiday shirts and trunks that have barely dried since the last swim. Elio and Oliver’s relationship is, by contrast, intense, furtive and passionate. It is the quintessential holiday romance, the sort that possesses your every waking moment and makes you lose your head, even, as per the title, your identity. The fact that the action takes place in 1983, to a soundtrack of The Psychedelic Furs and Mr Giorgio Moroder, makes it all the more sweetly nostalgic.

The 2007 novel by Mr André Aciman, from which the movie is adapted, ends with the pair meeting again, 20 years later, which Mr Guadagnino took as an invitation to create a sequel. Mr Aciman has now confirmed that he is writing a follow-up novel so, happily, this isn’t the end of Elio and Oliver after all.

At the end of Four Weddings And A Funeral, Ms Andie MacDowell’s Carrie utters the immortally daft line, “Is it still raining? I hadn’t noticed,” as raindrops pour from her eyebrows, cheekbones and chin. It’s the line that follows, though, that best sums up the lightly subversive spirit of Mr Richard Curtis’ film. “Do you think – after we’ve dried off, after we’ve spent lots more time together – you might agree not to marry me?” fumbles Mr Hugh Grant’s Charles. “And do you think not being married to me might maybe be something you could consider doing for the rest of your life?”

Charles and Carrie have been somewhat maligned over the years – the stumbling fop and the rainproof American – so it’s easy to forget that their relationship is rather grown-up and against the rom-com grain. Charles is the inexperienced ditz, Carrie the slinky, cool cat who calmly lists all the men she has ever slept with over a cup of coffee.

Neither actor has captured quite the same magic since. They weren’t even Mr Curtis’ first choice for the roles. The director dismissed Mr Grant as being “annoying, too good-looking and a bit posh” and wanted Mr Alex Jennings or Mr Alan Rickman (imagine!) instead. As for Carrie, Ms Sarah Jessica Parker was top of the list, long before she became the other Carrie in Sex And The City.

The great, undimmed joy of this film is that, across its various characters and plotlines, it offers a smorgasbord of romantic possibilities, from the thunderbolt to the homely, the lusty to the merely convenient and the unrequited. It posits that not all love has to end in marriage and that not all love need be romantic. Indeed, when American producers thought a funeral in the title might put audiences off, Charles And Chums was suggested as an alternative.

When Mr Norman Jewison’s heist movie was released in 1968, its directorial flourishes (in particular his use of a split screen) were met with mixed reviews. “As likely to enjoy an enthusiastic welcome at the box office as a chromium pickle fork in Tiffany’s deluxe Christmas wrap,” said The Hollywood Reporter. It remains, though, the sexiest cat-and-mouse movie there ever was. Mr Steve McQueen, the bank robber, in an ice-blue shirt to match his eyes, puffing on a cigar. Ms Faye Dunaway, in an array of sculptural hats that look like satellite dishes, the most glamorous insurance investigator of all time, sent to catch him.

Together, they create a heist with heart and somehow make both chess and the inner workings of the Internal Revenue Service throb with erotic potential. “Want to play?” asks Thomas. “Try me,” purrs Vicki in that infamous game of chess, which was later parodied in 1997’s Austin Powers.

The final scenes – Vicki waiting in a car to see if the law will catch up with Thomas, Thomas reclining in an aeroplane, waiting to see if Vicki will choose love or duty – are a study of how to play mixed emotions. The 1999 remake starring Mr Pierce Brosnan and Ms Rene Russo doesn’t even come close.