Short rule when creating the Kingdom of Sicily

[Side]

I was playing as the duke of Apulia and trying to create the Kingdom of Sicily. I spent a few years getting the money and piety required, and in the process I gained a Long Rule bonus to vassal opinion of about +15. When I created the kingdom and got the new title I suddenly had a penalty of about -15 due to a short rule.

The character was the same and the vassals were the same. Nothing changed except the ruler getting a fancy new title.

 

[BlckKnght]

This can also happen when you get a new second kingdom and make it your primary title, as I foolishly did as Harald I of Norway following my conquest of England. I'd really rather my Norwegian vassals remembered the decades I've ruled them back in the old country, as I have enough trouble suppressing the last few Saxon Dukes who rebel every few years!

 

[Myrten]

It happens when you advance a tier up, so when I usurped emperor title I got short rule with all my vassals despite the fact they were in another de jure kingdoms in which I had long rule before.