I read it as, Brody tried to behave normally and failed.  This is probably all the sex he's had for eight years - masturbating to images of his wife.  I think that he is still so isolated as to not want to be vulnerable.

Comparing apples and oranges.  Selling 6 million copies makes you popular, not influential.  Think about high school - how important are the head cheerleader and quarterback now, or the nerdy art kid.  The stuff with legs floats as time goes on; the other stuff is forgotten.