Confessing the couple's third child, Apollo, was not planned, the 46-year-old singer, who is now dating her fellow The Voice coach Blake Shelton, tells InStyle magazine she lost her way while trying to record album track with her band, No Doubt, in between school runs and family commitments.
"Getting pregnant, which wasn’t planned and was such a miracle, put me in a whole new spiritual place," she tells the new issue of the publication. "I was trying at the time to do more music with No Doubt. Then I got pregnant, and I was like, 'OK, well what am I gonna do now? I need to make some changes. There's only so much energy'."
She admits the last years of her marriage were not the happiest, especially when her now-estranged husband wasn't home.
"I didn’t tour at all, but I did record the No Doubt album, which was super hard," she explains.
"I was torn the whole time. Every day I would take the kids to school, drive to Santa Monica (in California), work on the album, and then I’d think, 'Oh my God, if I don't leave by 2.30, I’m not gonna get home in time for dinner'.
"And Gavin being on tour... I’m not gonna say there weren’t some incredible moments making that album. But it was a lot of knocking my head against the wall. A lot of struggle."
Gavin and Gwen announced the end of their 13-year marriage in August (15).
She went public with her new romance earlier this week (beg02Nov15) and was spotted holding hands with Shelton at a party following Wednesday night's (04Nov15) CMA Awards in Nashville, Tennessee.