There’s a case to be made that Roxette’s It Must Have Been Love – sung by Marie Fredriksson, who has died after a 17-year health battle – is the greatest 80s power ballad of them all, and perhaps the greatest breakup song.

It’s certainly one of the biggest. The epic chorus – “It must have been love, but it’s over now” – is the sort of thing anyone can bellow, in an arena or the bath. When I saw Roxette in Manchester in 2012, the signature tune was the climax of the night, greeted with massed singing and beach balls in the audience. Frederiksson was already visibly – and occasionally audibly – frail, and yet seemed to summon up vast reserves of passion and emotion, which she poured into the Swedish band’s biggest global hit.

Ironically, for a song which has been ubiquitous on the radio and in clubs for over 30 years, It Must Have Been Love started life in 1987 as a Swedish-only Christmas single (subtitled Christmas for the Broken Hearted). EMI Germany had asked Roxette’s songwriter Per Gessle for an “intelligent Christmas single”, but balked at releasing it internationally. In Sweden, it reached a more than respectable No 4, but it was inclusion in the 1990 romantic comedy Pretty Woman – starring Richard Gere and Julia Roberts – that saw it explode around the world, spend 14 weeks in the UK chart (reaching No 3) and propelled the soundtrack album to triple platinum status in the US. By the time Gessle submitted the song for consideration in the film, the duo had already scored two US No 1s. Meanwhile, perhaps crucially, It Must Have Been Love’s intro and outro had been given crisper edits and the line “It’s a hard Christmas day” had been changed to “It’s a hard winter’s day”, adding to the song’s universal appeal. It has subsequently notched up five million radio plays and earned an astonishing half a billion dollars.

Gessle, who as a child would sneak into his older brother’s room to play the likes of the Animals’ We Gotta Get Out of This Place and the Hollies’ He Ain’t Heavy, He’s My Brother – drew on years of appreciation of the transformative power of epic pop, as well as Swedish folk. However, perhaps because of their trademark 80s look (big hair, PVC and eyeliner), gated snare drums and squeaky synths, Roxette were long dismissed as pop fluff. Few bands claimed them as a source of inspiration. Oft-compared, hardly dissimilar Australian duo Savage Garden even made a point of insisting they were not influenced by Roxette. Gessle was unfazed, pointing out “in eight years, Abba never got a good review in Sweden”, making a not-inappropriate comparison with that other Swedish pop sensation.

Marie Frederiksson and Per Gessle performing in 2015. Photograph: Ullstein Bild/ullstein bild via Getty Images

As with Abba, jokes about Roxette’s hairdos and outfits have latterly given way to a more reverential appreciation of their craft. The 28-or-so artists who have covered It Must Have Been Love range from this year’s The X Factor: Celebrity winner Megan McKenna to Dame Shirley Bassey, and the tune powered its creators’ 2010 comeback arena tour. Roxette’s reunion was prompted when – after years of illness and inactivity – Fredriksson turned up unexpectedly at a Gessle solo gig. She was low on confidence, but her singing moved the audience to tears.

The song’s endurance is perhaps down to something deeper than a beautiful voice and a big chorus. It follows the old Motown blueprint in perfectly blending ecstasy (musical) with agony (lyrical). It’s a song about lost love, regret, and the feeling that the person singing it could – and should – have fought harder to keep the relationship alive. “It must have been good / but I lost it somehow” – the brutally wry understatement in that line has the gallows humour of the truly devastated. It also suggests that maybe she couldn’t have done anything, after all – baffled and alone, Fredriksson announces that love might never be understood.

For all the wistful heartbreak, it’s also necessary to move on – Fredriksson’s genius is in delivering the title line clean and stoic, rather than with tortured vibrato, to show that she’s resigned to her fate. But with the jarringly urgent upward key change in the middle eight, the pain floods in again, and she’s back to square one. It Must Have Been Love brings such torrid feelings together in a perfect four minutes and 15 seconds. Marie Fredriksson is no longer here to sing it, but Roxette’s signature song will never truly be over.