Complex sentence: Before her marriage to Pierre, which she undertakes purely for social and financial advantage, it is rumoured and later implied that Hélène has had an incestuous affair with her profligate brother, Anatole.
Split into simpler sentences: Before her marriage to Pierre, which she undertakes purely for social and financial advantage. It is rumoured and later implied that Hélène has had an incestuous affair with her profligate brother, Anatole.