If you have been together for a long time, congratulations! It sounds like your commitment has seen you through many tough periods.
But, is it that you have little need to change in your relationship, little motivation or energy at this point, or little reason to hope for better?
Lifelong habits are harder to break, but people can certainly change at any age. If you are going to stay together, why not make your remaining years together the most pleasant possible? If argument and pressure have not made things better, perhaps you would both like to try some other strategies. I can help you with those.