Complex sentence: His First Lady was the former model, Broadway actress and "Winner Take All" hostess Athalia Fetter, who became a prominent civil rights activist, which resulted in a rapid decline in her husband's popularity.
Split into simpler sentences: His First Lady was the former model, Broadway actress and "Winner Take All" hostess Athalia Fetter. She became a prominent civil rights activist, which resulted in a rapid decline in her husband's popularity.