It's primarily about fantasizing, with the hopes of one day living it out. The physical sensations are secondary.
Mental imagery can also partly explain why you shout another lover's name with a new one.
Saying you will only see porn behind closed eyes if you've watched lots of porn, but suddenly go noporn and take to facebook stalking, is like saying if you've only done acid, but suddenly quit and take to cannabis, you'll still be addicted to acid, have acid-like visuals, and be reminded only of acid-like experiences. When experience dictates you'll forget all about acid and be focused on the cannabis lifestyle. I can assure you, having watched plenty of porn in my day, I have no problem summoning fantastic images with girls I've seen in person or long-ago facebook stalked.
My only point was that the fantasies in your head shouldn't be your focus if they're all based on porn. In my experience there were times where it was nigh impossible to orgasm without thinking of pornographic fantasies/imagery.
Also your acid analogy isn't entirely accurate. I think if you took a lot of acid regularly, and then replaced it cannabis, you would at least be reminded to the psychedelic/altered state of consciousness experience, potentially even desiring the state from LSD again.
This thing is very anecdotal and personal, so it's very hard to generalize. I just throw all assumptions out the window when dealing with this.
Edited by Wingless, 07 February 2016 - 03:20 AM.