probably just the end of the bloom. Phals are a long lasting bloom but if you bought it in full bloom no way of knowing how long the bloom has previously been open. Now it is up to you to grow the plant so next year you will have a new set of flowers. Cut the spike and grow your plant.

I thought spikes weren't cut in hope of a kieki?

True about keikis but that should be only considered of plants that are robust. No picture of plant.

I'm rather new to Phals, but I do know that producing a keiki is a lot of hard work for the mother plant.
Since you can't be sure of conditions a new Orchid, esp a Big Box Store bought one was grown in or how long it was "on the shelf", I would assume the plant is stressed and not induce keikis this year. I would cut the spent flower spike and fertilize at the first sign of new growth.

I was also thinking that since it lost the blooms now would be a good time to repot and see what the media looks like,its spring so giving it fresh media would really benefit,and it would also give you a chance to see what sort of condition the roots are in.Velleta

Wilting flowers could be the result of overwatering or at least the result of the roots staying too wet and beginning to rot. Once this happens you will have to grow the plant drier (but humid!) to encourage new root growth

Phal blooms don't die all at once. Something caused it.

Jane