I guess I might see them running a kingdom the way they'd run a stereotypical old fashioned household. As in, him being the one more behind what would have been stereotyped as manly areas (military for example) and her being more behind what would have been stereotyped as more feminine areas (things relating to caring for their subjects, like helping the poor) and probably about even on things that didn't fit into one of those categories. I don't really see either of them as having it in them to be dominant rulers, but I could imagine them settling into stereotypical gender roles both as a couple and in the way they would rule.

^ I totally agree with you.