On television and in books, Christmas is often potrayed as a magical time when everyone is nice and loving to everyone, and everything is amazing. (This is actually true of most holidays.)
Real Christmas is not like that, even for people who absolutely love Christmas. Christmas is a difficult time of year. The time leading up to it is often stressful, overwhelming, and expensive. All of that is mixed in with some things that many people find amazing and wonderful (and that other people don’t so much care for.)
One aspect of Christmas that is often stressful is getting together with family. Even if everyone really wants to get together on Christmas, some aspect of it will suck. Because family is hard, even when everyone loves on another dearly. Holidays don’t heal family dynamics or make everything easy; people are the same people no matter what time of year it is. It’s particularly hard if you have relatives who are mean to you or bigoted towards you, but family gatherings have difficult and stressful aspects no matter how wonderful a family is.
No matter how much you like Christmas (or any other holiday), some aspect of it will probably suck. That’s ok. It’s not your fault. It doesn’t mean that you’re doing it wrong. It doesn’t mean you’re the Grinch. It just means that life is complicated and that holidays aren’t always easy.
tl;dr Christmas and other holidays have difficult, unpleasant, and stressful aspects as well as the uplifting and enjoyable parts. It’s normal to have mixed feelings about holidays and to find some aspects unpleasant. (It’s also ok if you dislike holidays altogether.)