When we first meet someone that we are attracted to, we have an inclination to be on our best behavior; to think about how our actions will look before we proceed. While this sounds like a good approach at first glance, we are beginning the relationship with deceit and not trusting that the other person will like us for who we really are.
By always being authentic, you act and react in your most natural way. When we are our genuine selve all the time, we learn more quickly who is and is not a good fit for us. We spend less time trying to fit the square peg into the round hole.
Once we are in a long standing relationship, the same rule remains. The opposite of being authentic is to be manipulative and controlling. If there is something you want or need from the other person, talk candidly about it. If your loved one cannot or will not respond as you would like, you have learned something new. You now have the opportunity to choose how to respond to them. Any reason you might have to act disingenuously is bound to lead you down a difficult path. Better to address the issue immediately and genuinely.