07/26/2009 AT 3:10 PM ET
Performing at the Deer Valley Music Festival in Utah, Rimes spoke to concert goers about the difficulties of being in a relationship.
“You know, I think that you will all really be able to relate to this next song in your lives. You probably know it’s inevitable that in a relationship, sometimes you will have your heart broken at some point,” she said. “Sometimes, you might say that you can’t do anything and sometimes, you want revenge. Sometimes, you say, ‘You’re not worth it.’ But sometimes, you don’t, and that’s when you leave it in God’s hands and know that he will take care of it.”
After reports surfaced that the singer was allegedly having an affair with her Northern Lights costar Eddie Cibrian, a source close to Rimes and Sheremet tells PEOPLE that their relationship may have simply run its course.
“They were so young when they got married, she was 19, he was 21,” the source says. “Maybe they just grew up and they weren’t in the same place anymore. I don’t think that’s unusual considering how young they were when they got married, and the business they’re in.”
Adds a friend of the couple: “They were so close, I believe that however the marriage works out, they will always be the best of friends.”