For the Iron Age haveing childrens at 15/16 its a normal thing, and if u want a second partener you need that both agree beeing with you, dont cheat your wife boys
That is kinda what happens, tetra gives birth to a boy while the princess a girl, since only the one from princess side can inherit, they need a boy, otherwise they would have to marry the 2 siblings to which mc freaks out
@SkDayVen It's generally now believed that for the middle ages the normal age to have children for the commoners was about the early 20's, is there any reason it would be lower in the iron age?
Though then again these are nobles so they marry and have children young.