Complex sentence: Like most of her sisters, she would never marry; she was a possible bride for her older cousin Louis of Orléans (1703-1752) but her aunt, the proud Duchess of Orléans wanted a more socially important marriage.
Split into simpler sentences: Like most of her sisters, she would never marry. She was considered as a possible bride for her older cousin, Louis of Orléans, but her aunt, the proud Duchess of Orléans, wanted a more socially important marriage.