Essentially, what this condition does, is cause the average male to grow progressively more and more stupid with all things related to females.
So, the guys start off okay, as their Stupidious Maximus is in recession, but as friendship approaches a relationship, their intelligence begins to drop like a rock. Some guys tend to start showing symptoms later in a relatioship than others, although unfortunately, these guys usually exhibit worse symptoms once they start.
This is why guys manage to screw up relationships so much. In the course of the relationship, they've gone from being a normal intelligent guy, to being a dumb as a post ignoramous.
Unfortunately, there is no known cure for Stupidious Maximus at this time, however there are a few rare guys out there who, though they carry the genetic disorder, seem to not suffer from it's symptoms.