Complex sentence: But, simultaneously, Angélique's harpsichord teacher, who would regularly enjoy the hospitality of the Diderot household, had become "persona non grata" in Diderot's house.It is conjectured that he may have made unwelcome advances towards Angélique.
Split into simpler sentences: But, simultaneously, Angélique's harpsichord teacher, who would regularly enjoy the hospitality of the Diderot household, had become "persona non grata" in Diderot's house. There is speculation that he may have made unwelcome advances towards Angélique.