Clandestine Affair

Two women hidden away deep in a mansion, who save each other through their roller coaster of a relationship!

Bai Yuetao, the wife of a rich businessman, blames herself for her husband's skirt-chasing. After getting all dressed up, only to spend another night alone in their lavish residence, she sees a graceful woman appear in her new mirror. This woman calls herself "Mengdie" and says that she can teach Bai Yuetao how to "hook" her husband's heart, but the price will be— Bai Yuetao's body.

(Source: Bilibili, translated)