So, as Navarra, I fight a very long war together with the Duchess of Burgundy and Normandy (a bunch of other duchys were also in on it) for the throne of France. Her consort and children were of my dynasty, and I was really looking forward to eventually having a Jimenez ruling France. And this was a really, really long war. It must've been at least a decade, maybe 15 years, during which I fought several other wars (against Beja-Algarve, Leon, Duke of Galicia, and a Christian Badajoz - these wars are worthy of a post of their own, by the way, they were awesome - and a crusade against Barcelona) and even spent some time just restoring my troops, and (still during the Burgundy-France war) the Duchess own son overthrew her and left her as just Duchess of Normandy. Then, after all these years and probably several dozen thousand of human lives, we finally beat back the Big Blue Blob enough to make them give in, and all is well; the Duchess is almost middle age and soon her son and my nephew will inherit the throne.
...Or so I thought. I go to war against Mallorca, and when I look back to France, all hell had broken loose, the Duchess had been excommunicated, several counties proclaimed independence, Leon had for some reason decided to wage an excommunication-war, and the fucking Capets declared war to take back the throne from their one province of Mainz (in which several of the nobles, that previously fought with the Duchess against the Capets, had joined in against her). And she doesn't call me to arms, so except getting the Pope to lift the excommunication, there's nothing I can do except watch the result of all that work fall to pieces. Now the Capets are back on the throne and the French Jiminez line back to just ruling little insignificant Burgundy.
I love this game.