My wife flies Portland to Denver every couple of months to help care for her elderly mom. She just went to book for February and there were basically no Frontier options at all unless she wanted some insane layover at four times the usual price.
She ended up booking Southwest instead. Paid around $300 with a layover, compared to the usual $50ish nonstop she normally gets on Frontier.
Did Frontier quietly pull a bunch of DEN routes or is this just seasonal schedule weirdness? Curious if anyone else is seeing the same thing.