Accidentally Swapped Husbands with My Eldest Sister

The eldest daughter of the Minister's Residence, Shen Yunshu, was betrothed to Pei Huaijin, the legitimate eldest grandson of the Grand Tutor's Mansion. One was graceful and dignified, the other composed and self-possessed; a truly well-matched couple.

Her younger sister, Shen Youran, was happy for her sister but also secretly relieved: her eldest sister, who micromanaged her like a daughter, was finally getting married. Now, no one would force her to read, practice calligraphy, play the zither, or paint every day!

Unexpectedly, Pei Huaijin had a younger brother named Pei Huaian. Though a bit of a rake, he wasn't a bad person and was quite handsome. After some investigation, her eldest sister felt he was a perfect match for the lazy but beautiful Shen Youran, and subsequently betrothed her as well.

Sisters became sisters-in-law, marrying on the same day with identical wedding dresses and dowries. Shen Youran, pouting beneath her red veil, followed her sister into the Grand Tutor's Mansion.

Fortunately, the groom was indeed as her eldest sister described: jade-like and golden, clear as pine wind and moonlight. Shen Youran closed her eyes and let him press her into the crimson soft quilt.

Suddenly, the door was pounded loudly. A frantic voice from outside cried: "It's a mistake! A mistake! The brides were sent to the wrong rooms!"

Shen Youran's eyes snapped open. She stammered, "Pei family... eldest brother?" The man above her trembled violently, his clear eyes wide. "Shen family... third young lady?"

This novel features two couples. The first features a traditional, rigid, 'daddy' male lead and a lazy, delicate, 'sister-fanatic' female lead. He attempts to 'tame' his wife after marriage but is instead tamed by her, ending up doting on his delicate wife to no end.

The second couple includes a rakish, pure-hearted younger brother and a soft, beautiful eldest sister. The pure-hearted younger brother can't resist flirting; just a touch from his sister makes him dream of romance.

Reading reminders: This is a sweet romance novel with a 'marriage first, then love' trope. There is no female rivalry between the sisters. The male and female leads are 5 years apart, and the secondary couple's siblings are 2 years apart. All characters are pure (virgin).