*shrug* Since I can never be bothered to write anything in the Journal part of the diary (can't be bothered, would rather just play the game), my journal never has anything particularly personal in it to begin with...and thus, having my loved one read it wouldn't bother me to much.
Having *everyone* in the party look at it and write frivolities into the margins seems inappropriate, though even that depends on how "close" everyone in the party is. The Knights of Myth Drannor--as written by Greenwood--tend to act like one big family having as much fun as they can while risking their lives, for example. A party made up of a bunch of best friends is bound to do any number of goofy, "inappropriate" types of things.