Tsunehiko Watanabe 
The Ideal Sponger Life: Volume 11 (Light Novel) [EPUB ebook] 

Burdens on both Aura’s time and body mean it’s finally time for her to appoint a prime minister and marshal. While the lightening of the load couldn’t be more welcome, the risk of those appointments pushing the country away from her control is stronger than ever.
With both that potential and her husband’s future in mind, she grants Zenjirou a dukedom to help maintain the balance of power. Coupled with even more guests from the Twin Kingdoms, the prince consort is in for a fair amount of personal upheaval, but now his wife wants him to head to the Northern Continent with his likely concubine-to-be as well!
It’s going to take quite a bit for Zenjirou to feel comfortable with the journey, but their current guests just might have the solution…