Both spouses deserve to be happy. If one or both are unhappy and the kids are grown, divorce should be an option. I don't believe divorce is a decision to take lightly though. I know what it feels like to be in a marriage that is miserable. I'd rather be single than married and unhappy. Sometimes there are things that just cannot be fixed. If your mate is not happy, even if you try to do things to make make your mate happier, it doesn't mean you can be successful. I sure do not want to be married to someone who is not happy to be married to me and vice versa.
I believe though that if there are kids still at home, a couple that has a congenial relationship should consider staying together until the children are grown and out of the house. If you know early enough while your kids are still growing, that you want to divorce, then it's wise to plan for a divorce financially during those years. While planning, don't forget that your children may need your help to pay for college and to get started on their own. And by all means work together as a team to help your children prepare for the real world. Show them that you can work together for the good of the family, while you are together.