I think you're hoping for way too much.
In order to have an actual Wedding this is what would need to happen:
- Kingdoms would need to stop declaring war (so Towns don't flip)
- Lords and Player all travel to a designated Town over several days (messing up where troops are located)
- Then presumably stay there for a day or longer
That would completely break the game as is. Whole game conceptually would have to be overhauled to make actual Feasts/Marriages possible. Though that probably wouldn't be a bad thing, since this game is a Military Industrialist's dream i.e. kill each other, wait a bit, then kill each other some more!