Jason Isbell and Amanda Shires are no longer in tune.

Isbell, 45, filed for divorce from Shires, 41, in December after more than 10 years of marriage, Rolling Stone reported Feb. 8, citing court records.

E! News has reached out to reps for the singer-songwriters for comment and has not heard back.

Over the years, the duo were not just partners personally but also professionally, as Shires played the fiddle and was a backup singer in Isbell's band, The 400 Unit, which has won seven Grammys. And The Killers of the Flower Moon actor reciprocated, by taking on a supporting role as a guitarist in The Highwomen, her supergroup with Brandi Carlile, Natalie Hemby and Maren Morris, which won a Grammy in 2021.

The couple has been open in the past about their marital problems, expressing their struggles in their music and onscreen. The lyrics of Shires' 2022 song "Fault Lines" allude to relationship strife. Meanwhile, tensions brewed between the two while Isbell was recording his 2020 album Reunions.

"At one point, I said, 'It'd be easier if somebody had cheated,'" he told The New York Times that year. "Then we could say, 'You did this,' or 'I did this,' and 'Somebody needs to be real sorry.' But it was more like, 'We don't know each other right now. We're not able to speak the same language.'"

Isbell and Shires—who share daughter Mercy, 8—appeared to once more be united last February, when they celebrated their 10th wedding anniversary and shared tributes to one another on Instagram. "Every day I wake up and fall in love with you again," he wrote to his wife, who said in her own post, "Cheers to all of the laughing, talking, laughing, traveling, dancing, laughing, growing, laughing, learning, laughing, loving and making music, a family and a life together. I love you very much."

But the following April, just months before the divorce filing, the former couple opened up about their marriage problems in Isbell's 2023 HBO documentary Running With Our Eyes Closed. In one scene, he alludes to a particularly heated moment between the two.

"My wife and I got in a spot that was probably pretty close to just calling the whole thing off," he said in a confessional. "She was offended by my behavior and I was offended by hers. We just kept our distance for a week or more. That's part of what made it so difficult for me, was the fact that we didn't know what to say to each other. We didn't know how to talk or communicate at that point in time."

As for Shires, in her own confessional, recalled, "He was being an a--hat. He wouldn't talk to me on the phone. He wouldn't respond to my text messages. I sent an email full of my thoughts and he didn't respond for like, f--king three days."

In that email, part of which she read on-camera, Shires tells her husband that she recently considered beginning marriage counseling with him. "Then I cried like a dingbat because this is what it has come to for me," she continues, "for us."