Important: This is a semi-fictionalized Tang Dynasty setting. The male lead isn't a scumbag in either of his two lives, but he suffers from a condition where he can chat and laugh with anyone, yet can't get a word out around the woman he loves. So there will be a groveling-to-win-her-back arc.
Not long after Emperor Gaozong of Tang made Wu Meiniang empress, the Liang State Duke's Fang family was wiped out after their daughter-in-law, Princess Gaoyang, plotted a rebellion.
Their adopted daughter, Fang Yizhu, was cast out by her husband's family and froze to death on the way into exile.
After being reborn, Fang Yizhu is determined to stop Princess Gaoyang from marrying into the Fang family again. She racks her brains to persuade her second brother, the "pitiful son-in-law of a princess," to visit brothels, beat up princes, run shady businesses, and debauch himself.
But to her utter surprise, her brother becomes the most popular, richest, and most celebrated young aristocrat in Chang'an.
At a loss, Fang Yizhu decides to trick her handsome, cold, and faithless ex-husband into pursuing Princess Gaoyang. That way, the two can marry and make each other's lives miserable, then hurry up and rebel together so they can all go down in flames.
But she never expected that her ex-husband, Cheng Chumo, who had paid her no attention during their three years of marriage in her previous life, would corner her in a dark alley one moonless night.
Fang Yizhu, tough on the outside but weak on the inside: "Scumbag, move aside. You're blocking my path to winning over Crown Prince Li Zhi."
Cheng Chumo pins her in the corner, brows furrowed and lips pressed together. "The crown prince? Haven't you been craving my body for ages?"
Fang Yizhu swallows, then faces the warm breath of the utterly gorgeous Cheng Chumo and forces herself to sound tough. "I wanted the wrong person in my last life. Can't I want someone else this time?"
The corners of Cheng Chumo's eyes redden. He speaks each word slowly. "No!"
Fang Yizhu: "Stop messing around. We were married in our last life, and we barely said a few words to each other."
Cheng Chumo lowers his eyes and murmurs, "I just have this condition where I can chat and laugh with anyone, but can't get a word out around the woman I love."
Fang Yizhu stares at him in surprise, but Cheng Chumo pulls her into his arms. "I know the Cheng family wronged you in your previous life. I rode twelve hundred li from the Turks, but I still came back too late to protect you."
Couple: Fang Yizhu x Cheng Chumo (a seemingly sweet heroine with a mind full of schemes x a male lead who is a warm-on-the-outside, cool-on-the-inside diplomat)
Premise: When you become a better person, everyone will love you