I just wanted to add to my answer up there a few pertinent facts. My ex and I were together for 20 years, married for 17 when we separated. We didn’t jump into our marriage, we truly loved one another, and we waited 7 or 8 years before having our first child. We had 3 terrific children together. There was no big affair or blowup, no abuse, we just grew in massively different ways.
While we didn’t often fight in front of our children, we were plainly unhappy. There was resentment on both sides, and a loss of respect. We recognized all of this as it was happening, and tried everything we could think of to get back on track and save our relationship… date nights, family time, weekend trips, and two different rounds of marriage counseling. In the end, none of it did the trick for more than a week or two.
While we truly did love one another (we held hands during our separation agreement meetings!), we finally recognized that we just could not live together anymore. It was the hardest decision we’ve ever made, and it was incredibly painful for all of us. However, if we had not made this decision, we all would have suffered far longer. As it is, everyone suffered but the suffering is over. We are all happy now.
I also rather resent hearing that we aren’t “finishing our jobs” as parents. Being a good parent =/= being married. We are both the same parents we always were, and have a very good relationship with one another and our children. They themselves will tell you that, while it was hard at the time, they are happier now than they were when we were together. So, if 5 people are happier, where exactly have we failed?