Time and again clients ask me if I shoot unposed pictures. My answer is YES, of course I like to capture my couples when they don't have to think about how they look or what they are doing. But to take a timeless unposed photograph takes more than just good timing. You have to know what is going on and be in a good position or you will never get the shot, period.
Being natural for me is about waiting until people are unaware the photographer isn't around. You have to be fly on the wall to observe these moments and as patient as an owl. Good natural photography isn't just standing in front of your couple asking them not to pose - that is just unstructured work that can only yield poor results. This is what I mean by natural and unposed: