Divorce is a very doorway to years of pain and dysfunctional for kids. There is a time for everything, a time to fight it through and say, "Dang-it, honey we're going to find a way to make this work for the kids." And a time to say, "No more, I'll not be abused and the kids will not be exposed to this kind of environment."
Either way, you have to understand that you decision, will effect the rest of your child's life. My mother divorced my Father when I was 2. She remarried two more times. My Father is on his 5th wife. They both are not happy but settling for their lives. Me and my two brothers and one sister have basically no relationship with our parents. Did my parents realize that this was going to happen? No. Most parents don't.
I love my parents both dearly, but it seems that with divorce- the separation that takes place, not only separates the parents, but as the one walks out the door, they take with them a part of the child's life. The child will, sooner or later, make a personal opinion about which parent was the better one. When they make that decision, they will inadvertently cut themselves off (even if only a little) emotionally, and socially from one of the two parents.
Later on as they mature, they will produce a favor for the one parent and a deep rooted hostility towards the other. Either way, when both parents make the decision to stop raisined and care for they're child together, as a whole, then dysfunction steps in and starts to raise the child.
When that child grows up and falls in love, the last thing that child wants to even consider the thought of divorce, and they're relationship with both parents changes again, and they become less involved, not wanting to be around, or listen to marriage advice from those who failed (in their opinion) at it.
There are some parents who have worked out a great plan to be separated but still share, care, and raise their children together. There are many families that go to counseling, and make all the right decisions in helping everyone cope with the divorce, never the less, divorce can be avoided by knowing who you are getting married to, and then continuing in the marriage to find better ways at being a great husband or wife.
I think that the biggest thing that parents can do, when they are talking about the possibility of divorce,is understanding that they are going to change their child's life forever. Then they can sit down with each other and discuss how they are going to help their children understand and grow up with it, and then set rules up so that the child is shielded (as much as possible) from all the issues that would cause that child to see one parent as worse than the other.