Ukkari Heika no Ko wo Ninshin shite shimaimashita: Ouhi Berta no Shouzou

Berta is wed to the king as his second wife in a loveless, political marriage. However, after Berta falls pregnant with his child, the royal palace is thrown into disarray. The king's first wife stews in jealousy and a deep-seated sense of betrayal as Berta and King Harold's relationship begins to change.

(Source: MANGA UP!)