Who is Juan Luz Contrera from The Last of the Menu Girls and what is their importance?

Though not a living character in the novel, Juan's presence is clearly felt. He was the first husband of Nieves and her obvious one true love. In Nieves's closet, there is a wedding picture that will remain there forever, showing Juan, who was considered a great "catch". He died about one year after marriage, having drunk acid, probably the result of the local druggist's mistake.