that is fine. Enjoy your second favorite team's success from a distance. Never cheer against BYU even if they are playing your second favorite team. Never sit in a student section of another school while they are playing BYU. I absolutely hate it when other school's students sit in the BYU student section.
If you are a Gonzaga fan first, then enjoy BYU sports from a distance.
If you still can't pick a favorite, cheer for BYU in Provo and cheer for the zags in Spokane.

I would just be a BYU fan.