And, to be honest, why *couldn't* the birthday party move? If he really wants them there, could the party not be held on a day close to the birthday, but still allowing them to come? If it's that important to Brother, surely a few days one way or another wouldn't matter?
Well, if you turn that the other way around, you'd end up with a question like 'My sister has asked me to move the date of my son's birthday celebrations to accommodate her yearly holiday' and I can imagine the kind of responses that would get.
I can sort of see where the brother is coming from. While there are logistical things in play here that affect attendance, it does seem like the OP is implying 'a holiday with my friends will always be more important to me than my nephew', so I can understand the hurt. That, rather than non attendance at this year's party, is what the brother is reacting to.
I don't know... to me honestly this feels like one of those "If you plan your event without me, then you plan it without
The OP isn't asking her brother to change the date of the party, she is just saying that she cannot attend the party on the date as it currently stands. Which seems reasonable to me. If it is that important to the brother that the OP be there at the birthday celebration, then he needs to make an effort to work with the OP's schedule so that she can attend.
The brother can be as hurt as he wants to be, but I think that he should also acknowledge his responsibility in creating the current situation. It sounds like he has never given his/his family's relationships
with the OP any importance (not visiting, passing through the area and not even making a token effort to drop by, blowing off her invitations to her events, etc) so it seems to me to be rather disingenuous (and self centered) that he is making such a big deal about the OP not being able to visit on this one day.
For the record, I don't see any problem with the OP saying to the brother, "Given that I already visit you several times a year, an afternoon birthday party on X date when you know we have a long-standing commitment is certainly less important to us then spending time with our friends, who we seldom see and one of whom has cancer."