Another manga I am trying to find

Had some pretty serious and mature themes. The manga was about a nation which was the combining of two ethnic groups separated mostly into two geographic region. Both groups don't like each other due to racism but are still in the same nation. The daughter of the king of the discriminated against group marries the emperor of the entire nation who is a part of the other group. The expectation was for the marriage to only last a year before being annulled due to lack of child. The emperor having never had a child despite years of trying. Except a child was born and now the ethnic tensions are rising because of a mixed race child now in line to be emperor. The story went on to cover the emperor's personal realizations about what this means for his life and the now really present systemic issues of his nation along with the empress coming to terms with what is going to happen in the future because of her child.

Any help finding it would be nice

Portrait of queen berta

thx for finding this for me