Complex sentence: After Agnes moves into Arnolphe's house, Horace arrives on the scene ahead of his father and Arnolphe's friend Oronte, and falls in love with Agnès and she with him.
Split into simpler sentences: After Agnes moves into Arnolphe's house, Horace arrives on the scene ahead of his father and Arnolphe's friend, Oronte. He immediately falls in love with Agnès and she with him.