I get the issue for the OP. The point is not that the birthday girl will be PO'd, it's the missus. "I can't go by myself and tell them you are home watching football". "If you loved me you'd give up the game to go with me because it's what we should do". Or maybe the dreaded, "what will people think about our marriage?" This is why these mixed marriages are such a difficult issue.
So, I think the answers are: heck yes get a to-go plate. You are already maybe sleeping on the couch, so might as well push it and see if you can get some leftovers. If you are going to do the time, might as well do the crime. My guess is the initial kerfuffle will last three days to a week, maybe less if she needs something done and you can sort of bargain it away. But you can probably expect to hear about it every time she's PO'd at you for, oh, say, the rest of your natural life.
Note: Mrs. uaintn would never expect me to miss an Alabama game, especially one of this magnitude, for something like this. Funeral probably, wedding maybe/maybe not, but a 30th birthday party, nope, no way. But she is an Alabama girl and was raised right, thank you Pop.