The entire point of the movie was that he was NOT the unfuckable dork he thought himself to be and he could've just dated her if he'd not been totally self-cucked. As MANY OF YOU are
Obsession was extremely popular because it fufills the female notion that every lonely mid guy is secretly a rapist monster and deserves to be miserable and alone.
It would have been a nothing movie if the genders were swapped.
Conversely if the rapist monster had been 6'3, extremely attractive, and a millionare, it would have also been a wild hit with women.