This photo was taken during the wedding ceremony in the church. Bride and groom are visible in the back, while the camera’s focus is on the groom’s father in the foreground. The long focal distance and the fully opened aperture used in this shot result in a very diffuse depiction of the bridal couple. This directs the viewer’s eye to the person in the foreground, who is watching the couple.
So the viewer is watching another person looking at the ultimate motif. This makes the picture interesting and somewhat of a generational photo.