Is knowing her necessary for him to be aroused? Does he have to have feelings for her for this to happen? Or do men in general get aroused simply because it is a part of their biological makeup? I've read somewhere that men are aroused by certain body parts on a woman... but I find it hard to believe that this could be so generalized. He has to like her first before he can be aroused, right?? As a woman, I have to like a guy first before he can arouse me... so is this not true for men too?
Also, how do you know he is aroused? (besides the obvious).