You sound like a child when you say "we are told etcetc"

Noone told you to get married. Noone told you that you have to not like porn. No-one told you that you have to do anything. YOU DECIDE. 

The purpose of life is that we make our own choices. Don't always assume that men or women always want to fuck the people in porn, it's purely visual stimulus that excites us sexually, aka, erotica. Part of being a responsible adult is not only making your own decisions, but owning up to them. If you are unhappy in life because you feel like every decision you made was done so with a societal expectation that goes against your inner instincts, then own up to that as your own mistake. If you honestly believe that humans are just meant to populate with as many different people as possible, do that. I think there's so much more value intrisicly and extrinsicly in forging long lasting, loyal relationships with others.