Complex sentence: Her marriage to Antoine was a romantic match, despite the fact that he was a notorious philanderer whose frequent absences left Jeanne in complete charge of the household which she managed with a firm and resolute hand.
Split into simpler sentences: Her marriage to Antoine was a romantic match, despite the fact that he was a notorious philanderer. His frequent absences left Jeanne in complete charge of a household which she managed with a firm and resolute hand.