I think i remember reading somewhere that your influence suffers if you break an alliance- though i've never tested it, and might have even dreamed it.

I usualy get around it by bundling tons of spies (and priests bishops) o stoke up a couple of rebellions and then mop.....

always thought it'd be cool to get vices and virtues for you king based on his relationships with other factions eg trustworthy, backstabber, babe magnet (for multiple marraige proposals)- thoughts?