In most eyes the color of the sclera (the white part) is a very light version of a person's skin coloring/complexion. In your image, sclera has a bluish tint. That can make the eye look somewhat unnatural, or clashing with the face.
Also what makes things a bit odd is that the eyes and the eyelashes and face is in a very sharp focus, but eyebrows are fuzzy.  

Lot of people don't pick up on thopse details, they just get the feeling of something being odd, or not fitting in quite right.

Actually for that matter, the hair, or at least parts of it could be more in focus. When there are out of focus parts, the human eye typically expects the pieces at the same distance from the viewer (eyes, nos, lips, ckin, eyebrows, eyelashes and any hair framing them) to be in the same focus. When different parts are of different sharpness, it makes things look odd.

The eyes are perhaps a bit too on the dark side compared to the rest of the detail around the eye.
In spite of those little details that may improve things, that's one great image you made. Love the way her skin looks.

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