Lily Allen and David Harbour have decided to end their relationship.

The 39-year-old “Smile” singer and the 49-year-old Stranger Things actor have separated after four years of marriage, according to various sources.

“Her marriage has been crumbling,” an insider tells PEOPLE exclusively, “and they have split.”

Representatives for Allen and Harbour did not immediately reply to PEOPLE’s request for comment.

Allen, who married Harbour in 2020 after meeting on the celebrity dating app Raya, hinted at a recent “tough time” in the December 16 edition of her BBC podcast Miss Me? with co-host Miquita Oliver.

Allen could not provide any further information on the root of her troubles, but she did say it was harming her mental health and creating her eating issues.

The pair married in Las Vegas in 2020, with an Elvis Presley lookalike officiating the event. Allen’s kids, Marnie Rose, 12, and Ethel Mary, 13, whom she has with ex-husband Sam Cooper, were also in attendance.

Earlier this year, Allen revealed some of the more unusual parts of her marriage to Harbour, such as her OnlyFans account, where she sells images of her feet, and how they controlled one another’s phone applications.

“I now have a children’s phone named Pinwheel. It does not support the internet or social media, but you can still use Uber and Spotify,” she told The Sunday Times in May. “My husband is the caretaker; therefore, he controls what apps I may have on my phone. I manage him as well.”

Then, in July, she stated on her podcast that Harbour considers her OnlyFans account “great.”

“At first, he was not turned on, but then he asked, ‘Is this a kink for you?’ And I was like, ‘No, that’s not a kink,’ but maybe there’s something in the power part that makes it slightly kinky for me,” she continued.

Allen also said on her podcast in June that she occasionally rejects her spouse in bed.

“I wonder if I kink-shame my husband,” she was saying. “I wonder if I kink-shame my husband,” she said.

“I’m not like, ‘You piece of s—, how dare you ask me to do that!'” Allen joked. “I’m simply like, ‘Hm, headache. I’ve got a little headache, so maybe not tonight.

In September 2023, Allen celebrated their three-year wedding anniversary with a romantic Instagram picture captioned, “3 years with this guy, 2nd best decision I ever made.” First, there was that clothing.

In November 2023, Harbour told PEOPLE about meeting his ideal partner in Allen.

“Let me tell you, my wife likes when I go to work because it’s nice for her to have her life and me to have my life and for us not to just annoy each other by being around all the time,” he told reporters at the time. “We have these two kids, and it’s wonderful. We get to raise kids, and as our marriage progresses, we get closer and closer.”

Allen and Harbour were originally linked in January 2019, when they attended the BAFTA Tea Party together, and their romance was confirmed in October.

Harbour announced their wedding with an Instagram photo captioned, “In a wedding officiated by the king himself, the people’s princess wed her devoted, low born, but kind credit card holder in a beautiful ceremony lit by the ashen skies courtesy of a burning state miles away in a global pandemic.”

Over the years, the two were open about their connection. In an interview with The Sunday Times in October 2020, Allen expressed her desire to have children with Harbour.

“I believe so.” Especially now that Marnie is getting so big,” she explained.

In June 2021, Harbour said on Jimmy Kimmel Live! that a chat he had with Allen’s daughters while riding their bikes pushed him to marry the singer.

“The little one was riding along, and she was going like, ‘David, Dad, David, Dad.’ Because the D got her confused,” according to the actor. “And the elder one became quite unhappy about it, which I understand. She was like, ‘He’s not our father! “He’s not our father!”

Harbour went on, “And then the younger one was like, ‘What is he? He’s kind of our father.” She says, ‘No, he’s not; he’s our stepfather. And she says, “What is he?” And she says, ‘He’s just some person in our life!’.”

The actor admitted that the girls’ talk inspired him to pursue the next step with their mother. “I was like, ‘I need to marry this woman,'” Harbour said. “Because of the emotional fallout …”

During an interview with British GQ in July 2022, the Stranger Things star reflected on the early days of their relationship, stating how he realized something was up with Allen after their third date.

“I was in this moment where I thought, ‘I’m just going to be brutally honest about everything,’ because why lie?” And I told her something about my life and my beliefs,” he explained. “It would take a really extraordinary person to be accepting of the things that I said.”

He remarked, “And I remember thinking, Wow, that’s somebody I want to be around.”

The couple frequently spotted the daughters out and about prior to their breakup. They attended the season 4 premiere of Stranger Things, a screening of Marvel’s Guardians of the Galaxy Vol. 3, and, most recently, Taylor Swift’s Eras Tour.