The Big fucked Nebraska 3 times with 3 season opening road games. Nebraska didn't have any leverage to say no. Its the God Damn league schedule.
Northwestern moved the game to Ireland because they got a big payday for moving the game. Again, Nebraska didn't have a lot of recourse.
As for the Colorado game, that only opened the season because the Akron game was called due to weather.
Nebraska literally had NO way to say no to any of those games.