The word "love" is over used in modern society so much. No wonder you feel the way to do. Your feelings are still there. They are just buried under a lot of talk, words and self doubt. You are not at fault for her actions.

Slow down, and develop a deeper connection to self. Self is a wonderful gift, given to us by the Universe. Do not throw it away.

Forget "Duty" and those "Musts", and just follow your Heart. Your feelings for your niece are very real. All your feelings are very real.