Who is Carl Neumann from Drowning Ruth and what is their importance?

Carl Neumann is a meat packer when he meets Mathilda Starkey, Carl is a good dancer who knows about horses, but has few prospects and no savings. His future in-laws look down on him. Carl plays drum in the Bayside Meatpackers Band when he and Mathilda meet at a Fourth of July parade. He is boyishly good-looking with brown hair falling over his eyes. In the course of the novel it begins to gray. Their marriage in December causes gossip.