As she prepares to throw the popcorn into his waiting mouth, the viewer is presented with a sense of anticipation.
This fact helps further the story for this l engagement session album.
You'll note my intentional use of his slightly bent knees—which aren't seen in the photograph but are reflected in his slightly crouched posture. That position implies impending action on his part.
His open mouth and raised chin also signal to viewers what they might expect to see next. You'll also note that both their arms are bent in such a way as to imply a sense of movement.
Before making this photo, I visualized a sequence of photographs that would help tell this portion of the story, thinking of ways that a playful couple might use popcorn to good effect.