Cavallari, 33, and Cutler, 36, announced on Sunday that they've chosen to get a divorce, but a source told People magazine that conversations between the couple about splitting had been going on for "a while."
"They have had divorce talks back and forth for a while," the source said. "They didn't want to get a divorce, because of the kids. Kristin has been very torn about it."
Divorce, however, was unavoidable, so Cavallari is focusing on moving forward with their kids -- Camden, 7; Jaxon, 5, and Saylor, 4 -- in mind.
"When she realized that it just wasn't possible for them to stay married, her focus was on keeping things amicable," the insider told the outlet.
"On their recent trip, they already knew they were splitting up," another insider previously told People. "Kristin and Jay had been having problems for a long time. They hadn’t spent much time together in recent months."
The documents said Cutler “is guilty of such inappropriate marital conduct as renders further cohabitation unsafe and improper."
Cutler and Cavallari tied the knot in 2013.
Cavallari's reps declined to comment and reps for Cutler did not immediately respond to Fox News' request for comment.