Fiction by Elizabeth Noble.
I liked this book a lot, although I'm not sure about the title. It seems to me to be more about the other relationships in the mother's life, rather than the one with the child. Although, of course, the mother/child thing colors everything in the woman's life...
Anyways, this story is about a woman and her relationships with her sister and her ex-husband (and said ex-husband's new girlfriend), as well as her relationships with all three of her children, one of whom happens to be dead. It's a good story.