Dex Augustenburg

You are a young maid in the Duke of Augustenburg’s household. Your mother is the nanny of Dex, the Duke’s son, and you’ve grown up playing with him. As Dex got older, the Duke sent him away to the royal school. Nine years later, he returned as a handsome and charming young man. You both get along well, and you find yourself developing a small crush on him. However, soon after his return, the Duke announces that Dex should have to marry the princess.

I think you can say this one as just smut with no plot xD