Lying in bed, a husband (Ben Affleck) strokes the silky blonde head of his wife (Rosamund Pike) and wonders, in voiceover, what happens inside that pretty skull of hers. If he could crack it wide open (and maybe he wants to) what would he find? This brilliantly unsettling scene bookends David Fincher’s adaptation of Gillian Flynn’s bestselling marital thriller Gone Girl. The scene is so effective because, for all the film’s excess and excitingly preposterous twists and turns, the essential unknowability of one’s spouse or lover is an anxiety at the heart of romantic relationships.

You can share your body, your bed, your bank account, and even your toothbrush, with another human being. But each mind contains a private world that can never be fully understood or examined, let alone shared with another – though we do keep on trying, especially in love’s first flush, when it feels almost possible for two people to merge into one single, harmonious consciousness.

But the effects of time and stress upon romance are terrifying, and Gone Girl fast-tracks its story from the meet-cute (complete with sugar-frosted first kiss and ravenous cunnilingus) through to suburban bleakness, unmasked contempt and suggestions of murder. And while nobody is going to call Gone Girl a commentary on modern marriage, like all good horror stories, it pokes and punctures familiar anxieties, providing a pleasurable lancing of the psychic boils that plague us.

What happens to the perfect couple when recession strikes and elderly parents need care? What if one of you turns out to be a narcissist, a sociopath, or something far more prosaic, like a lazy housewife or a cheating husband? As in the page-turning book, Nick (Affleck) and Amy (Pike) duel it out for the last word, inflicting violence of many kinds upon each other. In the hands of a director like Fincher (Fight Club, Se7en, House of Cards) the result was always going to be dark, bloody and compulsively watchable. It’s no wonder this surprising, thought-provoking and just plain fun film is currently topping box office lists.

For a less fantastical, but just as engrossing, examination of a marriage in crisis, check out the frequently hilarious and deeply perceptive Force Majeure. This Swedish psychodrama, directed by Ruben Östlund, seemed to come out of nowhere when it wowed critics and won the Jury Prize in Un Certain Regard at Cannes earlier this year (where it was also known by the title Turist). Set over five days in a skiing resort in the French Alps, the story centres upon an affluent, good-looking couple in their late thirties, Tomas (Johannes Kuhnke) and Ebba (Lisa Loven Kongsli). They’re on holiday with their two adorable pre-teen children. In early scenes we see the perfect nuclear family posing for photographs (a little awkwardly, it must be said, setting up a nice off-key tension), before sliding down the powdery white slopes in unison. After their wholesome exertions, they take an exhausted nap, the four of them in the one bed, like foxes in a den, all wearing matching blue thermal underwear. It’s a peaceful image inviting disruption.

The next day, as they’re eating lunch on a terrace, an avalanche looks set to wipe them out. The mother and the children scream. The father grabs his wallet and iPhone and runs for cover, saving himself without a backwards glance. Turns out it was a false alarm, but Ebba can’t forget the cowardly image of her husband fleeing, and after some initial denials and excuses, Tomas has his own crises of identity about his masculinity and his role as a husband and father.

Against the backdrop of majestic nature (Östlund began his career in skiing films, and captures the slopes with great feeling and grace) we see the puny human drama for what it is: both pitiful and momentous. Can this marriage survive? Can a woman love a man who is lily-livered? Can the man ever forgive himself for his selfish survival instincts? Bursts of intense Vivaldi underline the crisis as deadly serious, while also making fun of it. The way the conflict plays out in conversations between the couple and their friends over dinners and drinks (phone footage is watched and re-watched for verification and moral arguments are hashed and rehashed) is side-splittingly funny. And after it all, we’re left with the question: can we ever really know or trust ourselves, let alone another human being? And yet of course, we must, because civilisation itself depends upon it.

Gone Girl is in current release. Force Majeure releases 16 October.