It depends on how serious your relationship is. Have you met her parents?
I'm one of those old fuddy-duddys who think that octi should be reserved for the playoffs, but since this is as close as Dallas will get this year, it's kind of you to give them at least a taste of the playoff experience.
If you're really nervous about getting caught- wear a Stars jersey (get a cheap one at a thrift store) over a Wings t-shirt. If the jersey is white and the t-shirt red, you might need a white t-shirt over the red one to camo the red. Then once you get inside, give the Stars jersey to an underprivileged child (one whose parents haven't raised them as a Wings fan), ditch the white t-shirt (they're cheap at thrift stores) and wander about proudly wearing the Wings colours.
Or spend the game in a Stars jersey and when security asks who threw the octo, just shrug and ask them to explain icing.