Just lost my second campaign so far..
Not for a series of military blunders, I own half of England, conquered all of France, and moved into Italy out of necessity,.
Not for lack of money, I never went into debt although money was tight. (It takes some away from me, outside of the budget panel)
I keep losing because the third generation never gets married, all dieing of old age or falling to an assassin. No babies, no heirs, not even any generals to be recruited so I'm a little strapped here..
I don't know if you have to keep the family members holed up in cities for them to marry, (I always have every single able-bodied man out leading an army or with one), but if it is, then perhaps we should be able to recruit generals to make up for the lack of available commanders.
At first I associated this with the number of daughters I kept having, out of three sons each would have 3 daughters, one son. 9 useless princess's that I end up loading onto a ship..
I admit that I did not take every available option to get more heirs, IE adopting or marrying off a daughter.. or.. egh chase after enemy family members. I make it a point to try and preserve the original dynasty, but they sure don't help me much..