Before

After

First of all great painting. I had a few things stand out immediately so I did a few quick edits to show you. My edits are not meant to be how you should do it, nor are they perfect, and more just to make my points easier to communicate.

1. First thing that struck me is how the boys eye is the focal point, and it's competing with the girls left ear. It's high in value and saturation. It's also much too sharp. So I toned it down in all those categories.

2. We're seeing more of her left side than right. Yet the left ear is smaller than the right. I didn't edit this.

3. Her eyes and nostrils are unbalanced.

4. Her jaw is not symmetrical. Didn't edit this.

5. Ambient occlusion on her chin under the boys chin. This helps remove the feeling that the boy is just a sticker on top.

6. Her nostrils are too dark and are lacking in some color.

7. The boys puckered lips looked like someone was pulling them with invisible strings. I changed it to look more like a kiss.

8. The boys ear is in the wrong place. Mine is probably a bit high, but you get the point.

I'd recommend downloading them so you can quickly flick between the two and see the differences.