Bizarre as it may appear the use of a wedding ring by men wasn't common until fairly recently. ( Note that mens marriage rings and mens marriage bands are interchangeable, both meaning a similar thing. They were pleased to make public their dedication to their other half by the wearing of a public symbol that announced that dedication to all. And his wife may well regard it as a condition of the wedding that he do so. We all know the Celts, like Local folk of North America, viewed the earth itself as well as every aspect of life and death as divine. The natural world was considered holy, and each brook, mountain and tree had its own spirit of place. Early Celtic leaders even ridiculed human-like pictures of Olympian gods or the wild animals of their vale and forests. While anatomically wrong this makes for good fable.
It is commoner for the person's marriage ring to be wider than the girl's. A man on the other hand has wider chunkier fingers and so a wider man marriage band is more suited. For some more information on mens wedding rings