Complex sentence: In the summer of 1873 she became engaged to, and on 31 March 1874 married, William Michael Rossetti, son of Gabriele Rossetti and brother of Maria Francesca Rossetti, Dante Gabriel Rossetti and Christina Georgina Rossetti.
Split into simpler sentences: In the summer of 1873 she became engaged to William Michael Rossetti, and they married on 31 March 1874. William was the son of Gabriele Rossetti and the brother of Maria Francesca Rossetti, Dante Gabriel Rossetti and Christina Georgina Rossetti.