Jishou Akuyaku Reijou na Tsuma no Kansatsu Kiroku.

From Alpha Manga: Crown Prince Cecil married Bertia, who is a self-proclaimed "villainess." While they were enjoying their lives as newlyweds, Bertia received a request from her friend, Princess Risona of the Umube Kingdom, to produce her wedding ceremony. On their way to Umube, Bertia is being really excited, and Cecil has to support her. Original Web Serialization