In history, most personal/dynastic unions were short-lived, lasting decades at most. Why does EU4 display them as a permanent addition to your realm (as long as the opinion is positive, which is too easy to achieve)? At the very least, I think that aside from this system, there should be a much more common temporary personal union subject type, which always gets dissolved after the monarch's death, or at least spawning a large amount of pretender rebels upon their death.
The way they would happen is simple - Currently if a ruler dies issueless, the country they have a royal marriage with that has the most development has their dynasty put on the throne. I think there should be a chance to trigger this temporary PU instead.
The way they would happen is simple - Currently if a ruler dies issueless, the country they have a royal marriage with that has the most development has their dynasty put on the throne. I think there should be a chance to trigger this temporary PU instead.