Q.why are the fuzzy balls dropping off my pussy willow?
Why are the fuzzy balls dropping off my pussy willow? Just purchased this small weeping pussy willow tree. Instructions said to keep indoors first year & keep moist. All the ‘fuzzy balls’ have started dropping off. What’s wrong?

I also did a little research and saw where the tags of ornamental pussy willows said to "Keep the plant indoors for the first winter, and make sure it's well watered. Silvery white catkins will appear followed by yellow stamens later in the season." (http://www.bananas.org/f8/tree-enchantment-13239.html).
Did the catkins (the fuzzy balls) ever transform into yellow-stamened bottle-brush like flowers?

I have tried to find information about 'indoor Pussy Willow tree', but have been unable to find any variety that would be an indoor tree.
It's possible to have a Bonsai tree of a willow, but they also are not recommended for extended indoor stays.
If the catkins are dropping off, I would think the tree is under stress. Most likely not enough sunlight and or temperatures to warm in the house.
My recommendation would be to check back with the store where your plant was purchased and verify it's growing conditions.
Here is a link that has more information about Pussy Willows.
https://www.gardeningknowhow.com/ornamental/shrubs/pussy-willow/growing-pussy-willows.htm