If you wanted a story about softboy hero married to his op demon lord wife and they have a lovey-dovey relationship, too bad. I read until the stupid school tournament arch and the female lead shows no signs she'll stop hating his guts. The story is also all over the place. I have no idea what...
Fun fact: Blood is thicker than water is actually a shortened version of an older saying that has the opposite meaning. "The blood of the covenant is thicker than the water of the womb", meaning bonds forged by choice are stronger than bonds forged by birth.