For those of you who have trouble understanding George's reaction to Susan's death, I suggest you take some time to catch up on daytime trash talk TV shows (Jenny Jones, Montel Williams, Jerry Springer, Sally Jesse Rafael, Richard Bey, etc.). You will find out that the world is populated by its fair share of petty, malicious, uncaring, unfeeling, self-centered, small-minded jerks. Day in and day out you can witness a parade of pathetic losers who are pathologically incapable of carrying on normal human relationships. It's not uncommon on these programs to see ten year old children expressing a wish that their parents were dead, or adults who treat their children with such abuse that they might as well wich they were dead. And marital relationships? Forget it. There is enough evidence on these shows that marital vows of fidelity are not worth the paper they are printed on.
Therefore, I would submit that George is no different from the rather sizable portion of the population that is socially dysfunctional, and his callous reaction to Susan's death is wholly believable. In fact, a rather hilarious plot line for "Seinfeld" would be to have George appear on the Geraldo Show as part of a program on "Men Who Lose Their Fiances and Don't Care at All". That would be funny.