Some choose to stay because they have children and they are hoping beyond hope that their spouse will wake up and start responding to their pleas for attention, for marital counseling.
I understand this. When I said "one or both of the partners is too lazy to step up and make it work and/or too scared to end it," I meant exactly what you're saying. It takes both partners to make it work, and when one will not, it's doomed. I understand not wanting to leave for many reasons, especially if you have children. It's really sad when that's the case and your spouse has no desire to make things better. I'd hate to be caught in that situation, it would break my heart.
After years they get tired of repeating themselves to someone that never listens. Also sometimes money is a factor and anger is a factor of which you don't want to bear the brunt and so you go on just a little longer...Honey, my reasons are too complex and private to share here but they certainly don't involve lack of effort or an excuse to cheat.
All of this I understand. I'm not calling you out for your specific circumstances, I just have a jaded view of what someone looking to get laid calls a "dead marriage." To me, it's a really convenient excuse for some people to not work on their marriage and/or have extramarital affairs with less guilt.
I did fall in love with a man while still married and it was that relationship that forced me to get real and make decisions...but it just isn't that easy sometimes when you are coping with the death of a child on top of everything else. I am slowly, but surely moving forward...
I offer you my deepest and most sincere condolences on the death of your child. That has to be the one of the most devastating thing that could happen to anyone. I am glad to hear that you're moving forward. Moving forward when accompanied by pain and hardship is never easy.
I also don't think cheating is a mortal sin. It happens. And in your situation, it happened for reasons that are not hard to understand. I'm not condemning you. I was more just taking issue with how that phrase is used by some people. Sometimes there is a spouse at home who would be thrilled to work on this "dead marriage" if the other partner who is using that phrase to his/her paramour would try to work it out with them instead. But that doesn't sound like your situation to me at all.
I didn't mean to attack you personally, just comment on a phrase I hear batted around all the time.