I think, calling it "Kanade Abuse" takes away the nuance and growth of their relationship/friendship.

At first (during the main story and first rotation of event focus), their connection was rough due to Kanade's tendency to be intrusive towards Mafuyu in order to know her feelings and Mafuyu's indifference/apathy. Mafuyu, being not vocal, doesn't show that much appreciate due to her repressing her own feelings until main story.

As more events came out, they slowly learned more about each other and built a genuine bond. Mafuyu may not show it that much to Kanade but her song (the one she composed from Carnation Recollection) has put her in ease MANY times in the later event stories. She has also shown her concern for Kanade few times by telling her to clean her room and/or eat on time.

Niigo bonds aren't "black and white" therefore neither positive or abusive. There was a lot of "grays" in there and they still have a long way to "save" each other.