I'll hop in on this one with an unpopular opinion. Go to the wedding. Weddings happen ONCE. You can DVR the game and enjoy it just as much - other than you'll probably know who won by then, which can be a spoiler.
I got married on a game day and was pretty annoyed that some of my "friends" didn't bother coming to my wedding. Granted, it was
OK State at Arrowhead in 1998 and not the last Big 12 Championship game that Nebraska will ever be in, possibly the last game against Oklahoma in the forseeable future .....
Hmm....watch the game. You can watch the wedding on DVD afterwards.
No...wait....go to the wedding.
Bah....you make the call. :dunno