What???????
I can suspect two different things at one time.
1. Omaha NE winters - when at their frigid Arctic best - do not agree with the sensitivities of the elegant Viburnum plicatum f. tomentosum 'Mariesii'.
2. Your individual plant came to your landscape as a container grown plant. If you did not bare root it, or take any extensive measures to ensure it did not have drastically circling roots, it probably had very congested encircling roots which eventually "strangled" itself - leading to a situation such as you are presently observing.
IMNTBHO: you should take this as an object lesson, and do some serious horticultural CSI forensics.
Dig up that plant, wash all the soil off the root mass, and see what you find. Take plenty of photographs of the process, and post them all here for ALL to see and learn from. If I'm right, you will find a spiraling congested mass of older roots that roughly mimic the shape of the container it was grown in, with newer roots trying to grow outward while the original roots have strangled the plant in an ever-expanding vise-like grip of death.
Should've pursued Shakespearean acting...
