Simplify the following text for a Grade 5 native English-speaking person.
Original: In 1956 , he married the American writer Joy Gresham , 17 years his junior , who died four years later of cancer at the age of 45 .
Simplified: In 1956 , he married Joy Gresham , an American writer . She was 17 years younger than he was , and died four years later because of cancer .