Moreover, realism usually turns out pretty sad. Most of us are not going to take it well if a person we get in a relationship with cheats on us or even suggests that they want another person to join. I have seen a handful of projects that handle it 'realistically' most of them end with a sad 'you lose and are alone' ending. That's a serious boner killer.
But almost all media is realistic and unrealistic. We want the person writing our taut military sci-fi thriller to have served in the military, so they can give us the details that draw us into the world. But at the same time, no one wants to hear about how BORING being a soldier is 99% when you aren't under fire. Porn is no different. People want to be thrilled and entertained. It's not a bad thing.