When a male is hounded by many (mostly attractive) females for a relationship of some sort (in the fashion of Akito Tenkawa from Martian Successor Nadesico). This constant stream of females causes one to act differently, inducing dread instead of joy when in contact with said females.
Those who do not have a Tenkawa Complex cannot understand why those who do have one dread it. There's usually a good reason these types do not have the problem (looks, personality, intelligence, or combinations of the three are lacking somehow).