Simplify the following text for a Grade 15 native English-speaking person.
Original: It is during the summer of 1772 , a few months after his wife had given birth to a stillborn daughter , that began Philippe 's secret liaison with one of her ladies-in-waiting , StÃ phanie FÃ licitÃ Ducrest de St-Albin , comtesse de Genlis , the niece of Madame de Montesson , the morganatic wife of Philippe 's father .
Simplified: It is during the summer of 1772 , a few months after his wife had given birth to a stillborn daughter , that began Philippe 's secret liaison with one of her ladies-in-waiting , Madame de Genlis , the niece of Madame de Montesson , the morganatic wife of Philippe 's father .