TL;DR:
Northwestern could not play their games at USC and UCLA because they were scheduled for the peak of the wildfires ravenging LA at the time.
Now it is announced that those games will not be rescheduled. The Big Ten has therefore decided to give Northwestern two forfiet losses and award USC and UCLA forfiet wins. And now Northwestern might not make the Big Ten tournment.
Seems ridiculous and arbitrary since the games were canceled because of issues on USC/UCLA's end of things. It wasn't NW's decision not to play.