The Game Of Thrones star, 27, and the US singer, 34, announced this month that they were calling time on their relationship.
And it has now emerged that Turner is suing Jonas - requesting that he return their two young children to England, their "habitual residence".
It’s all a far cry from their fairytale romance, which started around four years ago.
So what went wrong? We have a look back at the couple’s relationship and split.
Pair were linked in 2016
Turner and Jonas were first romantically linked in 2016 after being introduced by mutual friends but kept their budding romance to themselves.
However, there were little teasers, such as Turner sharing a picture of Jonas on a boat and the day they were spotted together at a Kings of Leon concert.
And in 2017 the actor did tell Marie Claire in an interview that she was “very happy” with her beau.
Jonas popped the question in 2017.
The pair shared their engagement news with fans in a sweet Instagram post of Turner’s hand sporting a huge diamond ring, with the caption: “I said yes.”
Reports claimed the sparkler was worth a whopping $150,000 (£122,000).
Surprise wedding in Las Vegas
The pair didn’t say too much about their romance and many fans were stunned when they tied the knot in Las Vegas in May 2019.
Not long afterwards they had a second ceremony in France, this time with friends and family present.
Turner, who starred as Sansa Stark in the fantasy television series, later shared a snap of her and Jonas looking smitten as they walked down the aisle after exchanging vows.
Turner told The Sunday Times that she and Jonas did split up once, just for a day.
“It was the worst day of our lives,” she said.
“For a second we both had cold feet, then 24 hours later we were both, like, ‘Never mind’.”
Starting a family
Just over a year after their wedding, the pair welcomed a daughter.
Turner had been seen sporting what looked like a baby bump but the pair were typically low key about impending parenthood.
Willa was born in July 2020, and the couple confirmed the news to People, with their reps saying at the time: “Sophie Turner and Joe Jonas are delighted to announce the birth of their baby.”
Last year baby rumours started swirling again and it was reported that Turner and Jonas had added a second baby girl to their family.
They confirmed their new arrival but not release her name.
Earlier this month it was reported that Jonas had lined up a lawyer, with gossip site TMZ quoting a source as saying the pair had had “serious problems" for at least six months.
Soon afterwards Jonas and Turner confirmed they had ended their relationship, posting a joint statement online which said: “After four wonderful years of marriage we have mutually decided to amicably end our marriage.
"There are many speculative narratives as to why but, truly this is a united decision."
Turner sues Jonas
Two weeks after announcing they were splitting, Turner sued her ex, asking that their children be returned to England.
According to the BBC, lawyers for Turner filed a legal petition citing the "wrongful detention" of their children in New York.
The pair – who had made England their “permanent home” – had apparently agreed that their daughters could travel to the US in August but that it was supposed to be temporary.
Watch: What we know about Joe Jonas and Sophie Turner's divorce