How does Connie become an obsessive preoccupation with the stranger?

Oates does a really strong and commendable job of being
able to bring out the idea of how individuals are not really in control of their image
with all of society. There are some elements that will misread and misunderstand,
despite our beliefs that everything has been "controlled" and designed in a particular
manner.  It is here where Connie is located.  She believes that she is in control of her
own identity and her own image.  When she goes out that night to the restaurant, she
sees herself as being in control of everything around her and those who look at her. 
While she is bored with Eddy, she starts to notice Arnold.  Her continual looks of
flirting and interest are what awakens Arnold and his predatory instinct towards her. 
In the saddest of ways, Connie got what she wanted.  Her entire motivation to carry
herself in a particular manner, the obsession about her looks as well as the strict
definition of herself against her family, ended up causing her to be "noticed."  The
sadness here is that she is noticed by the wrong people, by someone like Arnold Friend
who takes to stalking and eventually abducting her.  It is here were Oates makes clear
the idea that we are not entirely in control of the image that we send across to
others.  Connie becomes a target of Arnold, whose obsessive preoccupation becomes the
end result of her desire to be "someone."