I planted a proven winners dwarf buddleia earlier in the spring and it did marvelously. It grew significantly and flowered beautifully. The flowers started falling off as expected and I didn't check it for a week or so and found it as pictured. The other photo is the same bush from late June.
No idea what could have happened, but hoping this is all above the ground and there is a chance it comes back.
I am in 7a and the new flower bed I planted this in is definitely wetter than I expected. It drains slowly.
And yes, I am both a new gardener and sometimes unreasonably optimistic!
I had a similar thing happen with some shasta daisies around the same time and there are already green leaves growing out of that wreckage.