The female lead transmigrates because of a hairpin. At first, she meets the Fourteenth Prince, and later they become confidants, nothing more. But the Fourteenth Prince falls for her.
The Thirteenth Prince also falls for her, and she falls for him too.
The female rival, Zhao Jia Wanzhi, the Thirteenth Prince's wife, is initially friends with the female lead, but later falls for the Thirteenth Prince, who does not love her. Wanzhi and the female lead become enemies.
In the end, by order of the Kangxi Emperor, the Thirteenth Prince is forced to marry Wanzhi. Heartbroken and helpless, the female lead puts on the hairpin and transmigrates back to the modern world.
Save this for later, and read it slowly once it's fully read.
It's a new article, let me take another look.