Are there any Morale upgrading buildings

[mfberg]

Watchtower/Border forts, and the townwatch and upgrades increase the loyalty of the province. Build these up and keep the 100+ people there to keep rebellions down. Some provinces such as Latvia, Lithuania, Scotland, Portugal, etc., also have more rebellious populations, so you will need more troops there to keep the rebellions down, or fewer to have smaller rebellions that you can mop up quickly.

mfberg

[HopAlongBunny]

mfberg lists the crucial builds for loyalty. A church will help to convert the region to your religion if that is a problem.

I usually garrison newly conquered areas with a stack of peasants until the builds are complete; 2 stacks for the mentioned "rebelious" provinces.

I don't expand very fast and except for early in the game I keep loyalty around 200%.