Most people have illusions abouts sth but when they are disillusioned their illusions go away and they see things as they really are. Dark and ugly.
The disillusionment of pakistani people with their status quo politicians is probably complete although not so with their military.
That one night of drunkenness wherein you find out (by accident, serendipity, or some twist of fate) that your girl friends don't exactly think you're as pretty as you think you are.
Girl: Who's prettier, Jane or me???
Friend: (pauses) You know how when someone is SO evil that even though they're really pretty they like, not look so pretty anymore? I think Jane's like that..
And that, folks, is Disillusionment.