I saw a headline recently (CNN?) that divorces in your age group are on the rise because people nowadays expect to live much longer and do not want to settle for less than a satisfying life (I am paraphrasing the headline). Why not consider it? If you call it quits now, you are likely to still remain friends, but if you continue on the trajectory you have outlined in your posts, you will eventually be out of that option, too, due to the accumulated bitterness.