Masturbation, for men, is a very different sensation from sex. It's harder, faster, firmer and done at a different angle. A vagina feels pretty loose and squishy by comparison, plus few women enjoy thrusting at the breakneck speed most men masturbate (if they ccan even do it that fast.)
I've got no idea why so many people, especially women, refuse to comprehend this. You only have to watch a man giving himself a hand-job to see how different it is to sex.
Men whose primary sexual activity is mastubation end up having a problem with PIV sex. Porn use exacerbates the problem - the brain associates the feeling of sexual stimulation and release with the images, pretty much forgetting about the entirely different pleasures of sex with a warm-blooded human.
I'm not making this up; it's a simplification of why porn addiction happens. You can easily find out about it on the Web.
As someone who's never been particularly impressed by gooey-eyed, soppy sex, SGB, I maintain there is a world of difference between fucking someone who's enjoying fucking you and someone who's 'using' you as a prop for the movie in his head ... or, same actually, if he's only interested in his feelings to the point he's almost forgotten who you are.
I have been guilty of this myself at times; I have a strong imagination. My partners noticed and disliked it, just as I did.