I don't think this is imaginary at all. Not exactly the same thing but I watched this documentary about a mother who had severe depression, so couldn't bond with her daughter. The child was only 5 months old but would look away from her mothers' face because she was distressed- and for me that was just so surprising to watch. I think as children we need others to help regulate our emotions, I can understand why her lack of emotional response can be upsetting.

Have you told her all of this?