Fetishes are formed in the brain in early youth. Example: a small child first becomes aware of their genitals at the same time they are looking at their babysitter's feet, and develop an abnormal interest in feet, which at the onset of puberty becomes sexual. Fetishes are involuntary. What you're describing (a sexual interest only brought on by porn) is "a kink" which is not the same thing as a fetish.
Someone with a fetish does not have to like the person or even find them attractive to be turned on by the fetish. "I'm attracted to people with brown eyes" is very different from "I involuntarily pop a boner when I see someone light up a cigarette."