Well OP, you’ve been married longer than I’ve been alive, so giving advice feels strange, but here goes. You have many options. The two best, in my opinion, are as follows:
1. Finagle the situation to make it tolerable.
Ensure the game will be on at the dinner. Be direct but good-natured about it. Take control of the situation, not in a brazen, bullish way, but in a positive way. Don’t just tag along; make your presence felt at this thing. Offer to help the friend you’re visiting with the set up or food, bring him a bottle of whiskey, something that is assertive in a positive, generous way. Or see if you can get the time or venue changed; offer to grill up ribs for everybody at your place instead! What’s your relationship with the host like, do you have a rapport with him?
2. Consider this a down payment on the future.
Be pleasant about the dinner itself. Tell your wife you’re excited to go, even, but explain that football season is dear to you and you only get 12 UT football Saturdays a year! Be direct, but not harsh. Be earnest, don’t pout. Make sure she’s aware that you don’t object to going along with plans of hers or spending time with her friends, but that UT football Saturdays are sacrosanct. Be clear that you won’t be able to attend social gatherings during game time in the future.
At the dinner, be grace and charm personified (before the game is on; after kickoff all bets are off, but still be nice to the people around you. Trash talk the OU fans in a good-natured way). You are showing your wife that you value the things she cares about (social outings with her friends) and in return you expect her to value the things you care about.
Above all, don’t listen to the people telling you to make an ass out of yourself at dinner. Flatly refusing to go is better than that, but still won’t be best for you long-term. You don’t want her to develop negative associations with you watching football and have to re-litigate this argument 3 or four times a season. You want to nip it in the bud now. Be strong and considerate, and expect the same consideration in return. Be a man standing up for his right to enjoy a favored passtime; some in here are encouraging you to be a toddler pouting over his favorite toy.
Godspeed, brother.