I could technically arrange Christmas in an order so that 1 year I got the kids, next year he did etc. Only on 'his' year, I wouldn't even have DD4 if I did that, and I know I would never cope with Christmas completely alone. So I never ask for them over Christmas to enable me to keep DD4 with me and 'survive' the season.
We usually go on holiday to escape it but this year my holiday ends on the 19th so Christmas is an issue.
I too think it isn't fair to expect divorced people to have Christmas together, especially in our volatile sitch, but Andy's parents divorced and they still spent every Christmas together. I remember Christmases as a child where I would be at Andy's house and both of his parents were sitting round the table for the Christmas dinner even though they were divorced.
They did the same for birthdays, special ocassions, doctor visits. It was so friendly between them, that his mother's new husband used to go round to his fathers house to mow his lawn for him.
So Andy just thinks that divorced people are supposed to be together over Christmas because that is his normality.
My parents never did that and I think it's crazy, but his whole family always do that. All the ex's are always invited to everything. MIL still wanted me to go round there to start with, until it went wrong several times and I then stopped accepting invitations.