Welcome to the Org, Ripken.

Sometimes the AI is just plain stingy with their princesses, no matter what you do. It's true that being too huge (where you own a third of the map or more) makes it almost impossible to get your sons married off. If you're only moderately big, however--around 15 provinces or so--that can work in your favor, as your faction leader is likely to have higher influence (which helps with securing royal marriages). Ironically enough, smaller factions have fairly good luck with getting princesses to marry their heirs--although why this is, I've never fully understood. You're also more likely to get princesses from factions whose borders aren't directly touching yours.

Still, none of these things guarantee your son will be able to obtain a wife. I've had a number of games where I couldn't get my sons married off, no matter what I did! It's unfortunate, but them's the breaks.

Quote Originally Posted by macsen rufus
On occasion you might have a claim on the lands of a faction whose princess one of your princes is married to though. It's never happened for me, but there are people in the Org who've won in that particular lottery!
I would be one of them. Expansion by marriage/inheritance is quite nice!