Married into the Marquis's Estate as a Substitute Bride, I Became the Heir's Cherished One

[Completed + devoted couple + marriage before love + groveling pursuit of his wife + period setting] The Shen family's eldest daughter had been betrothed to the heir of the Marquis of Changning for years. Shen Youyi eagerly looked forward to her wedding, but when the heir suddenly contracted a terrible illness at fourteen, the imperial physicians declared that he would not live past twenty. Unwilling to bear the shame of breaking their promise, the Shen family brought back Shen Ruchu, the illegitimate daughter born to a prostitute, and made her marry into the marquis's household in her half-sister's place. With no other choice, Shen Ruchu could only hope to live quietly in the marquis's residence and keep her mother safe for the rest of her life. But an edict left behind by the late emperor drew her into a shocking conspiracy. Only then did she realize that the heir, said by everyone to be gravely ill, was hiding another identity! The heir, too, gradually discovered that his new wife, who seemed honest, sweet, and meek, was no pushover at all. She was a ruthless woman who hid her true abilities and played the pig to eat the tiger. Married before love, they test each other at every turn, clashing like needle and awl. He goes from cold indifference to falling for her, then suffers through a bittersweet, grueling pursuit to win her back. She goes from silently protecting herself to opening her heart, and eventually becomes the one he cherishes above all others for the rest of his life. Some marriages are written in the stars. After all the twists and turns, they discover that everything they ever wanted was right beside them all along.