Flowers opening and wilting

[camille1585]

A pot overflowing with roots will not cause a Phal problems. If anything, they prefer to be snug in their pots rather than having lots of space.

It looks like you keep the plants between a window and curtain? It can get really cool at night next to a window, and Phals being rather tropical plants, they generally don't like it.
Or is there heating right under the window? The warm dry air coming up does dry out plants and can make blooms wilt prematurely.

Lastly, how long ago did you get the plant? If you just got it a few days / a week ago, in bud or with a few blooms open, they could simply be blasting from the change of conditions between a nice greenhouse, a shop, the trip to your home and then your home conditions. This happens frequently unfortunately...