Taking vacation near holidays

In my dept we're only 2 EAs. I have 10 years of experience with 3 years in this company. My peer is 5 years shy from retirement and has been in this company more than 15. I support the President and VP/GMs while she supports VPs and a few Directors.

We cover for each other when we take vacation and she's been taking the weeks on Thanksgiving and Christmas off for a while, even before I arrived. The first year here I didn't care... Last year I had family visiting on Thanksgiving and could take it off because she had already submitted her request. This year she asked me about it because she felt bad, but the thing is me and my family don't tend to plan those events a year in advance... I told her I'll plan to take Christmas Eve off for now, in case de decide to do something... And she put vacation for Thanksgiving week and Dec 21-23, like 2 minutes after I responded to her email.

I find this a little rude and unfair, but I guess it's my fault for not making November/December plans in March... Am I being unfair? Is she being unfair? I don't want this to strain our relationship and I don't really know how to react. I hate that this is even an issue.