The woman/girl's face doesn't look very girly, she looks like she's got a flat nose stretching all the way to the right of her face (this may be because the girl in your reference pic is looking in a different direction than the one in your pixel art). She also reminds me of Mona Lisa for some reason. The guy's face is alright.
Though in general, I think the faces use too many colours for such a small size, it makes them look blurry (again, the girl in particular).