Complex sentence: His usual bad manners toward her was so noted that the opposite was seen as a surprise: in 1726, Sophia Dorothea inherited a sum of three million from her mother, and Frederick William was noted to suddenly treat her very well.
Split into simpler sentences: His usual bad manners toward her were so noted that the opposite was seen as a surprise. In 1726 Sophia Dorothea inherited a sum of three million from her mother, and Frederick William was noted to suddenly treat her very well.