Shadowed Thrones (from Dramabox) or it may also be known as I am the Supreme.
It is a story about a guy Felix Young who is the ruler of a country known as the Fuminican who goes into seclusion to hide his identity to marry his childhood love whom he knows through a jade pendant. He marries her best friend who was gifted the jade pendant. He oversees her promotion to high status from the shadows for her to be happy but is divorced by her when she is promoted. He finds out that his wife wasn’t his childhood love but her best friend was. Later, at the feast for her promotion, he reveals his identity but is deemed an impostor, later recognised and then again deemed an impostor.