You've confused the words die hard with bandwagon.
As for the OP, your heart will make the decision for you. Iknow my brain didn't decide to root for Kentucky. Kentucky was playing LSU on tv and basic human instinct took over.
You can say, I'm not a Cowboys fan. But if the game is on and you're happy when they score and pissed when they don't, you still want to be a fan. You should just go with that.
But also, if Dak throws a pick, and you find yourself clapping and flipping off Jerry Jones shots in the owners box, congratulations, the spell is broken. And there is nothing wrong with that.