Adele and her CEO husband Simon Konecki had been "living separate lives for years" according to friends close to the couple.
Yesterday, a representative for the superstar singer confirmed the couple had separated and requested privacy.
But The Sun reports the couple had not been happy for a long time and the news came as little surprise to those close to them.
"This is a very sad situation - Adele and Simon had been living separate lives for some time," a source told The Sun.
"It was well known amongst their friends that this time they simply were not going to sort it out.
"They had been trying for years but eventually you have to accept that something just isn't going to work."
The notoriously private couple began dating eight years ago and have a six-year-old son Angelo together. The pair married in secret three years ago, with Adele finally confirming the marriage when she accepted a Grammy Award at the 2017 ceremony.
During the emotional speech, she tearfully announced: " 'I'm married! My husband, my son, you're the only reason I do it."
45-year-old Konecki was born in the United States but spent his teenage years in London, where he attended the prestigious Eton College, alongside Bear Grylls and Tom Parker Bowles.
After beginning his career in finance, he founded an eco-friendly bottled water company Life Water, before moving into the charity sector, establishing Drop4Drop, which helps provide clean water in third world countries.
Konecki was previously married and has a nine-year-old daughter with his ex-wife Clary Fisher, from whom he separated in 2008.
Konecki and Adele began dating in 2011 although it's never been confirmed how or when the pair met exactly. Rumours that Ed Sheeran introduced the pair were shut down by the singer, who tweeted: "Despite what some papers believe, I had nothing to do with Adele meeting her boyfriend. Dunno where that rumour came from."
The couple were first pictured together in Florida in 2012, near where Konecki's parents live in Boca Raton.
In a rare interview, Adele spoke about her relationship, telling Vanity Fair it was "the most serious relationship I've ever been in."
"All of my relationships are more important to me than any tour I'll ever do. If my relationship with Simon or my relationship with Angelo started to flounder a bit now, I would pull out of my tour," she said in the 2016 cover story, ahead of her record-setting world tour, which saw her play three sellout shows in Auckland in 2017.
"He's not threatened by any stage of my life that I'm going for, and that's an amazing thing," she said.
The couple were last seen together publicly at an Elton John concert in Los Angeles in January.
Adele rose to prominence in 2008 when she released her debut album 19, which featured the hit singles Hometown Glory and Chasing Pavements, and was nominated for the 2008 Mercury Prize.
However, it was her second album 21 that saw her hit superstar status, featuring the heart-wrenching breakup anthem Someone Like You. Released in 2011, the record went on to become the highest selling record of the 21st Century and won Album of the Year at the Grammy Awards. To date, it has sold a staggering 31 million copies.
Four years later, Adele released her third album 25, featuring the global hits Hello and Send My Love (To Your New Lover). Again, the album broke sales records and went on to win six Grammy Awards, including Album of the Year.
Fans have been eagerly awaiting a new release from the singer, who has been on hiatus since the completed her global tour in 2017.
With the sad news of her marriage breakdown, some anticipate a new record will be on its ways soon, full of the bittersweet melancholy that Adele does so well.