First, is this a happy accident or did YOU set this up? Candid or not we still have to decide the lens focal-length, the proper f-stop ( not just for exposure-that's a given-but for THIS kind of depth-of-field). You NAILED depth-of-field, exposure, and YOU DID NOT USE FLASH! BRAVO!!!
Nearly everybody on this site and even on the Professional forums think they must destroy the three dimensionality of their portraits and FILL Flash everything!
When I'm doing candids at weddings THIS is what I do if there is ANY available light.
Good Job! Jerry V.