Hindsight always seem so perfect. But it's not. Chances are were any of us tossed back into our original circumstances and time the outcome would be exactly the same. Just as with your first marriage, GM, our ethics, upbringing, social milieu, religion, etc. all have their place in how and why things take the path they do. This is far deeper than a simple lesson learned situation. When we advise others to jump ship and shortcut the process, sometimes we just find that we are undercutting their values.
Like you, from one perspective I spent far too much time in a failed marriage. 20 years! I know that at the end I had concluded that I couldn't live with myself unless I had tried and exhausted every possibility to salvage things. I did that. Unfortunately, it also took me many years to really understand where my responsibilities were in the situation. I had to change to get to the point where I could actually try – really try. It was probably too late anyway and there are circumstances which rendered my efforts irrelevant anyway I suppose. Hard lesson… But what are you going to do?