Who is Sophia Rothschild Swain from Slapstick: Or, Lonesome No More! and what is their importance?

Sophia Rothschild Swain is Wilbur's second wife. At the time of their marriage, Wibur is 72, and Sophia is 23. Unfortunately, Wilbur doesn't love his wife, and she later leaves him for a condominium in Machu Picchu.