Add that to his crazy, always changing schedule and you have one very frustrated girlfriend.
I get annoyed when he isn't off on weekends and I want him to go to a party or I find myself alone with no one to hang out with.
What sort of celebration will it be if half those present are angry about the means used to get them there?
Many of the harshest disagreements are over someone's insistence that the family do things the same way as in the past, despite the problems that doing so would present.
If in the end someone is asked to sacrifice, they will probably feel better about doing so if there has been an effort to take their input into account.
When family members disagree as to when, where, or how the family will gather, don't squelch their differences by imposing a flat decision.
It's dangerous to assume that nothing is different.
Instead, encourage them to talk to each other, having them explain their positions and seek to find a compromise acceptable to everyone.
In discussing differences, try to get everyone to listen at least as much as they speak.
This year, for example, I know of a son, whose job requires that he work Thanksgiving evening, who is in conflict with his mom, who insists that the family follow their tradition of getting together late that afternoon.
Traditions are worthwhile only if they provide more benefits than complications for those who follow them.