What does being authentic mean when it comes to authentic sex? Can sex be credible? Sounds kind of strange, but yeah, sex can be credible (and not just the factual kind). Sex might also include trust and certainly sex could mean being real.
So what is "authentic sex"?
When we are choosing to engage in "authentic sex", we are present for sex. That means we are fully there- emotionally, mentally, and physically. We hope that each time a person chooses to have sex, they are all in, for all 3 of those areas, but that doesn't always happen. Authentic sex allows partners to be at their most aware - from listening to their own bodies, feeling the sensations, being in-tune with their emotions, and even finding ways to get better for the next time.
So the bottom line- if you're having sex or doing something with your partner that you want to eventually improve upon - do it authentically.
Information adapted from http://www.psychologytoday.com/collections/201208/tell-the-truth/sex-and-authenticity