As an amateur social theorist, a watcher of human relations and with my experiences of being myself...I've had certain consistent results come through, over a period of time, based on which I have come to the conclusion that under some specific conditions a person can become invisible or even completely disappear.
Here's my pseudocode for this condition:
IF
(AGE >= x) &
(STATUS = 'SINGLE') &
(LOOKS IN ('UGLY','FAT','NOT CUTE'))
THEN
{
DISAPPEAR_FLAG = 'Y' WHERE GROUP = 'ALL_FRIENDS';
OVERRIDE_DISAPPEAR = 'Y' WHERE GROUP IN ('FAMILY','TROUBLE@WORK','BILL_PAYMENTS')
}
ELSE
{
DISAPPEAR_FLAG = 'N';--FOR ALL GROUP
OVERRIDE_DISAPPEAR = 'Y'; --FOR ALL GROUP
}
The silver lining for this is that the blurring of existence is only on the physical plane.
In cyberspace you are as alive as the frequency of your social networking/microblogging site updates.
That way you can have friends who'll know what you are up to without them actually having to be with you (or care in the very least).
And that works great for them.
Here's my semi-autobiographical panel-