Was it very sunny? Most pink peonies fade...

Both plants get a lot of sun. This hasn't happened in the two previous years when they bloom.

If it was sunnier and HOTTER than usual, you'd get increased rate of fading.

My Raspberry Sundae (2nd year of bloom) was VERY pale this year and last - although not white. I've been very disappointed.
Although, come to think of it, the spring turned very dry (around 3 inches below normal in late April-May) after a wetter-than-normal start (2 inches above normal rainfall for March-part of April). I wonder if that was the cause for me?