Another Divorce

I am a little sad about Al and Tipper Gore. After 40 years together, why get divorced? Don't they want to spend their 70s and 80s in the company of someone else who remembers when their children were little, and their first apartment, and all the crazy things that have happened to them? Sure, they spend most of their time apart now, but so do lots of power couples. What do they see down the road that makes them want to end their marriage now? I can only think that either they can no longer stand the sight of each other, or that one or both of them is deeply sad and hopes to be saved from coldness and emptiness by a new romance. It seems a little crazy to me. Good luck to them both.