Labug:
I will add more details later, but just wanted to quickly say that I *want* to have a clear agreement for exactly the reason you said. But he keeps resisting ("I think we can just be flexible and mutually respectful, and work things out as they come up.")

So, he said, "what's your preference for this holiday?" I replied, "you get first preference this year". He replied, "I know but I was asking in the hopes we can come to a mutually beneficial arrangement" for this particular arrangement, rather than him "dictating" what he wants this year.

In theory, it's generous and collaborative of him. And I actually don't doubt that he has noble intentions. But it's as if he has this vision of la-dee-da divorce where things magically work out easily for everyone and we just get along fabulously. He can't bear to be the bad guy. But in some ways this felt worse. "What's your preference, Claire?" (While secretly hoping my preference is what will magically work best for him too, so there will be no conflict!)

What about a response like this:
Well, that is my preference, but since you are entitled to your first choice this year, here is another scenario that will work for me. And next year I will get my first choice.

Help me revise, please-- I know that is too blunt and sounds bitter but I'm tired and fighting a cold and busy at work right now.


Me 38 H 40
D 3
T 8 M 6
BD 10/2013