Maybe...instead of being sad...you could look at it as a sign of your own personal growth. I have seen you change from a poolboy into a man and...maybe...that is where it is.
Maybe this is all to help us grow,to bring us to apoint where we feel we have a choice...freewill and all. Maybe it is to help us recognize our own authentic selves. Maybe it is to bring us to a point where we fight for ourselves as least asmuch as we fought for our marriages.
Sometimes there is unknown strength in letting go...in discovering we are so much more than part of a set.
You know in your heart what your answer is because you are a grown-up...she stays, she leaves, she comesback...whatever.