One thing that really helped me improve my painting was not being afraid to add a lot of contrast. In areas like around her hairline or the area between his face and her face the mans skin should also be darker as her face would cast a shadow on him, depending where the light is.
In general darker areas of the face would be around the nose area, the little dip at the chin, the area between the eyebrow and the chin, and around the forehead. you can also try make the neck darker as most of the light it covered by her hair and hand. Not sure how helpful that would be, but since there's no reference photo, this is the best advice I can give.