This is a good example of the traditional and favored Hollywood 'fountain' lighting.
Not easy to do, but the effects can be wonderful, especially with multiple sources. This was a single on-camera flash unit, set to allow for backlighting, hence the smooth feel to it.
Very intimate contact made in this composition with the tight crop. The lines through the eyes and down the noses create interesting dynamics. The tones are bang on for my monitor! Eb