Different culture, different world, its kinda rude to judge, until a few centuries ago people used to cut each others heads, public executions, comment about age difference on this kind of world makes no sense, people from royalty and nobles from the real world used to born married, even before pregnancy there was deals for the first child being married with the first child of other family, or even unborn child's with "old" people.
It's no big deal, at least they had somewhat of a choice on the matter.