ghostbongweedofthesamurai:

7/14/2014 Toady One Slightly changed the way dwarves enter into romantic relationships.  Individual dwarfs are now assigned a desirability rating determined by the total point value of all skill levels learned, value of items in possession, and quality of desirable physical traits (which are different for each civilization and determined at world creation.)  Matching was supposed to work by assigning dwarfs to partners with similar ratings, but due to a small oversight they were continuously entering into relationships until the combined rating of all partners equaled their own.  This created problems when the king arrived and quickly appropriated a large amount of wealth, dramatically increasing his desirability rating and causing all the female dwarves to leave their partners for him.  The resulting negative thoughts created by the loss of partners plus the inability to find new ones lead to a number of violent rampages, eventually causing the collapse of the fortress.