Who is Joan's Husband from A Year by the Sea: Thoughts of an Unfinished Woman and what is their importance?

Joan's husband is never named, which implies that, for this narrative, he is only a peripheral character, only defined by his relationship to Joan. This is the opposite of the way Joan had seen most of their marriage, since she always felt that her husband's needs were more important, while she tried to handle the role of wife and caretaker.