Books 1 and 2: The beginning until Eustacia and Clym get married.
Books 3 and 4: Eustacia and Clym's marriage goes increasingly south, Mrs. Yeobright dies in the novel's climax, and Clym and Eustacia part after a huge argument.
Books 5 and 6: It's the death and marriage section. Half the cast dies tragically, and the rest get endings ranging from OK to happy.