I think the lighting works well, and it's a pleasing capture of this nice looking couple, however the faces may be a bit overexposed, particularly the man's. Try a shadow/highlight adjustment of about 4/10, and see if you like that any better. Are the man and woman different distances from the main light? If so, it might have been better to rotate them a bit clockwise, such that the man is farther to the back and the woman closer. This might help also improve the apparent relative size of their heads as well. Also, is that an aRGB file you posted? Looks that way to me, and if so, it's best to convert to sRGB for internet use.
Regarding Tom's observations, I think the images are the same - we just have our eyeballs set to their default aperture-priority. When one views an image against a white background versus a darker one, the eye will compensate like a camera, reducing the aperture to darken the image. A medium gray background is best.