Andrew Haigh’s astoudingly realistic film 45 Years is at once an advertisement for marriage and a cautionary tale against it.

Happily child-free and on the cusp of celebrating their 45th wedding anniversary, Kate and Geoff Mercer have settled into a comfortable, peaceful daily rhythm.

This is rudely interrupted, however, when Geoff receives a phone that will irrevocably change their marriage.

The body of his first love, a woman named Katya who died falling from a glacier while the pair were travelling through Switzerland, has been found.

With this news, Geoff retreats into a bizarre haze of nostalgia, referring to his lost love as “my Katya”, flipping through old photos late at night and obsessing over his carefree youth.

As Geoff, Tom Courtenay (The Quartet, Doctor Zhivago) captures this descent into bumbling fixation perfectly. He is frustratingly pathetic as the loyal and loving husband having a late-life crisis while his beautiful wife struggles to stay patient.

Of course, Best Actress Oscar nominee Charlotte Rampling is the standout in this quiet, reserved film – which hits home not for its gripping action but for its lack thereof.

As Kate, Rampling is reserved, polite and tolerant until her jealousy and resentment bubbles over, shattering her cool, calm exterior to devastating effect.

• Joy review
• Steve Jobs review
• Deadpool review

The pair share an undeniable chemistry and some of their lighter moments – dancing around the living room or going for long morning walks together – are beautifully genuine and an ode to the contented ease of a long-term relationship.

Music is used to great effect throughout, with upbeat retro romance tunes gaining an eerie sense of solemnity when contrasted with the melancholy of Kate and Geoff’s interactions.

The use of The Platters’ 1958 version of ‘Smoke Gets in Your Eyes’ is particularly poignant.

45 Years is a hard film to watch, but unlike other awards season favourites like The Revenant or Room, it’s not because of shock factor or gruesome violence.

Rather, Haigh has crafted a film that is uncomfortably realistic. You feel as though you’re watching Kate and Geoff’s marriage unravel through a peephole.

It’s an insight none of us asked for, but it’s impossible to look away.