I have an opposite issue. I played a Vlandian character, mostly recruited Vlandian wanderers, and have focused mostly on conquering Vlandian fiefs. I got good and rich as Western Empire vassal before declaring my own kingdom, and made friends with all the Vlandian lords (mostly be defeating them and letting them go, repeatedly). All my garrisons are strong, I've brought plenty of lords over to join my kingdom.
End result - nobody wants to have a war with me. In reality, that would be the logical choice - Mexico isn't going to declare war on the US in hopes of gaining San Diego, they would be crushed. In the game it means the only time I have war is when I declare it, which also means it happens when convenient to me. Keeping my lands and people happy is not a challenge because my parties are on defensive mode mopping up bandits and I wander around assigning companions to complete all the quests.
I actually want more war. I'd like to see the Empire factions make a mutual aid treaty with the Aserai or whoever to divide my forces and challenge my ability to hold onto my territory a bit. When I am mopping up the final Vlandian town (Ocs Hall) a smart move for the AI would be to declare war on my Eastern or Northern front. Presumably Derthert would be lobbying hard and offering them all sorts of things to get their help.
Instead they fight each other over fiefs somewhere else and let me continue slowly consuming the map.