Impersonated Groom Betrothed Bride

A countryside girl journeys to the capital to fulfill her childhood betrothal with the second son of the prestigious Pei family. She marries a man she believes is her intended fiancé, finding him unexpectedly gentle and attentive despite cruel rumors. Three months later his nephew returns and confronts him in shock. The devastating truth emerges that the husband she wed has been impersonating his own nephew all along. Who truly belongs to this arranged marriage?