Back out on some of their commitments. Draw close to the Lord and pray together. Marriage therapy helps a little, but it looks at the interpersonal relationship like communication skills, dealing with conflict . . . It's got to be attended to at some time. Individual counseling and then getting back together.
Dysfunction comes when they've wounded each other.
There's a lot of forgiveness that needs to go on. The kids naturally want Mom and Dad together. It's easier for younger kids to accept a divorce than older kids. Once they get into junior high and use an abstract form of thinking, divorce is much more distressful. Children no longer have two active parents.