Simply Complicated
Shouma was a gentle man. In most things he went with the flow of life rather than trying to fight the current.
His life wasn't typical, but he kept things simple enough no matter how extraordinary the circumstances were. And there was no shortage of extraordinary circumstances where his wife was involved.
Conrad might not have taken any particular notice of the exceedingly average man except for his uncharacteristic command that the foreign prince not show his unpleasant face to the man's family. And almost as soon as the Earth mazoku made his ultimatum he slipped back into his naturally calm, peaceful attitude that both infuriated and compelled the Shin Makoku resident.
For years to come Conrad would wonder if he kissed Yuuri's father that night to test him or to steal some of whatever magic he used to get through life.