Task: Question Generation
Input (English):  After having haughtily refused a number of suitors, under the pretext that they are not peers of France,  milie de Fontaine falls in love with a mysterious young man who quietly appeared at the village dance at Sceaux. Despite his refined appearance and aristocratic bearing, the unknown (Maximilien Longueville) never tells his identity and seems interested in nobody but his sister, a sickly young girl. But he is not insensible to the attention  milie gives him and he accepts the invitation of  milie s father, the Comte de Fontaine.  milie and Maximilien soon fall in love. The Comte de Fontaine, concerned for his daughter, decides to investigate this mysterious young man, and he discovers him on the Rue du Sentier, a simple cloth merchant, which horrifies  milie. Piqued, she marries a 72-year-old uncle for his title of Vice Admiral, the Comte de Kergarou t.
Several years after her marriage,  milie discovers that Maximilien is not a clothier at all, but in fact a Vicomte de Longueville who has become a Peer of France. The young man finally explains why he secretly tended a store: he did it in order to support his family, sacrificing himself for his sick sister and for his brother, who had departed the country.
Output (English): Why does the Comte de Fontaine investigate Maximilien?