Would it be wrong to spend thanksgiving alone?
Is there some reason you want to be alone for Thanksgiving?
I'm lonely and my friends are all occupied on Thanksgiving
I'm sorry that you are alone on the holiday.   Is it still possible for you to visit your family during part of the day on Thanksgiving? Families like spending time together during holidays, and they will be glad to see you if you can make it.
Who cares? I didn't agree with them to have Thanksgiving together and I'm not going to meet them.
It's your choice to make, but I'm sure your loved ones would be happy to see you during Thanksgiving even if you weren't expected to be there. No one should have to be alone on that special day, and you would be welcomed into your family's home, if that is what you want.