I accept that you disagree with me, but IMO, if you have to TELL someone what they have done wrong, then it SHOWS that, to them, they haven't done ANYTHING wrong.
Because if they thought they had done something wrong - then they wouldn't need telling WHAT they had done wrong. And if they DON'T think that they have done anything wrong, then that shows an amazingly high level of lack of thought for the other person involved.
In the OP's case, if I was the OP, I would first of all have expected my DP to stick to the arrangements we had made together to spend Christmas at home with the dc. I would also have expected him NOT to have gone behind my back and make alternative arrangements without my input. I would also have expected him to think about how I wouldn't enjoy spending Christmas with my mother, as he would KNOW the issues there. On top of that, I would expect him to know how it would feel to know that the person who is meant to love you doesn't want to spend Christmas with me. I would have an AWFUL lot of unmet expectations in this situation, and I would be reeling at the level of selfishness my partner was displaying, and would be very concerned as to whether that selfishness was going to carry on after the birth of the twins.
If someone is upset with me - I will sit down and think of nothing else except how I may have upset them, until I KNOW why they are upset, and I understand their upset, and can make a PROPER apology, and see things from their point of view. I expect the same from other people in return.
I would have thought it was normal to expect other people, and certainly someone that you are sharing your life with, like a DP, to do this, to sit and think about what they have done to upset someone? In fact - I would expect them to sit and think about the impact of their actions on their loved ones BEFORE they take those actions. Because I would. Am I really that abnormal for taking the time to think through the impact of things like this on other people BEFORE taking action?