Risou no Himo Seikatsu
I found this series (from what is fan translated) very enjoyable. It is an isekai about an ordinary Salaryman named Yamai Zenjirou. He is summoned to another world and asked if he would be willing to marry the queen.
The fun part about this series is that it gives a compelling reason for these events. The queen is a holder of a special magic that exists within the royal line is dying out. The society is very paternalistic so if she marries a noble from within the world she will be kicked from the throne and hidden away to bear babies. So she used magic to search other worlds to find a male with magic capability from a rumored line that broke away from the royal family in the distant past. Hence Yamai Zenjirou is summoned.
What is nice is that he is given a choice. Stay in his existing world (alone and working lots of OT in the existing modern world) or become her husband and sponge off her in the paternalistic fantasy world.
As the series progresses, Yamai Zenjirou and the queen fall head over heals in love with each other and Yamai Zenjirou begins to take an active role in the political realm to help out his wife.
It makes an interesting story with the equality minded Yamai Zenjirou wanting to be a monogamist in a society where the nobles wants him to be paternalistic minded and a polygamist in order gain royal influence and to increase the people capable of his type of magic.