You have to change your attitude to sex altogether.
1) It's not a performance
2) No-one is watching you and rating your prowess
3) Sex starts waaaaaay before penetration. It starts with the very first date. So it's not about "being a man" and shoving it in.
4) The REAL reason why you ejaculate is OVER-EXCITEMENT... so try and calm down... spend more time on foreplay...
5) Practice Practice Practice... on your own... WITHOUT PORN (the goal is to calm down). Start... then stop just before you ejaculate... repeat... for as long as you can... for as long as it takes... the goal is to gain an understanding of your arousal so you can keep it under control.
6) once again... IT'S NOT ABOUT PENETRATION.
7) IT'S NOT ABOUT PENETRATION
8) Sex is a wonderous and mystical JOURNEY... it's not a destination.
If you would like to watch a movie that deals with sex, male sexuality and some other more mature themes...
check out: "Bliss"
http://www.imdb.com/title/tt0118742/
It's the only movie that deals with the mysticism behind male sexuality that I have come across. Maybe it'll spark an interest and you'll research some of the themes they discuss.
p.s. The movie gets pretty hectic... there be dragons in the shadows. Adults only, and not just because of the sexuality theme... the movie touches on the aftermath of abuse. And if that is a sensitive issue, no other movie brought it home quite like this one.