Kelly Clarkson and Brandon Blackstock's marriage problems were "exacerbated" in quarantine.

Kelly Clarkson

Kelly Clarkson

The 38-year-old singer filed for divorce from music manager Brandon, 43, earlier this month after seven years of marriage and the Covid-19 lockdown reportedly deepened the cracks in the relationship.

A source close to the couple told PEOPLE: "It was a stressful time. Quarantining exacerbated any issues."

Another insider revealed that work had put a lot of strain on their relationship and the pair - who have children River Rose, six, and Remington Alexander, four, together - had "been like friends for a while".

The source explained: "Things had changed in their marriage and the split was a while coming. They both work so hard. It's nearly impossible to enjoy each other, especially with the children needing constant attention.

"Kelly's been through a lot, and she thought Brandon was her happily ever after. It's very sad."

Kelly and Brandon had been quarantining together in Montana with their kids and his children, Savannah, 17, and 13-year-old Seth from a previous relationship, and Kelly previously admitted it was an "emotional rollercoaster".

In an interview on 'Glamour Unfiltered', conducted before she split from Brandon, she said: "Honestly, I have been on an emotional roller coaster. This has been really hard as a working parent, because I'm still doing all the same jobs.

"It's been exhausting honestly, cooking every meal and cleaning nonstop after toddlers and teenagers! Everybody's learning from home now and the teaching! So, everything has been crazy.

"I'm literally holding down so many things right now. Not only jobs, but even things where we usually had a lot more help.

"We are fortunate, so I'm not complaining in that sense, but I've definitely had to tell people that I work with, 'You hired a mom and I'm not an absentee mom. I'm a full-on mom.' I already have abandonment issues, so I don't want to pass those down."