Ankoku Kishi Monogatari ~Yuusha wo Taosu Tameni Maou ni Shoukansaremashita~ Chapter 56 part4 Discussion

So forget everything you've read in other reviews, on the wiki, or in the novel description. The premise of this story is that romance causes IQs to drop. The more romantic interests/entanglements/rivals, the bigger the drop, but only in relation to the other individuals involved.

Join our lead brick protagonist, his rivals, companions, and friends, as they journey onwards to see who can best misread the mood, miss subtext, and totally fail to understand every relationship they find themselves in.

Also, the story is pretty good too, unless you want anyone in the story to have a clue about what's going on.