Simplify the following text for a Grade 7 native English-speaking person.
Original: The Duke of Burgundy , who dearly loved his wife and who had stayed by her side throughout the fatal illness , contracted the disease and died on 18 February , six days after her at the ChÃ cents teau de Marly .
Simplified: The Duke of Burgundy , who dearly loved his wife and who had stayed by her side throughout the fatal illness , contracted the disease and died on 18 February , six days after her . He died at the ChÃ cents teau de Marly at the age of 29 .