Well obviously she’s had feeling for him since they were younger. That’s why in the first chapter when she was like “we should date for real...lol Jk!” she had that pained look on her face.
At some point somebody is going to come along and dispel all his slave magic bonds and the girls with stand with him because they all really care about him. Because like he said his magic can control the body and the mind but it can’t control the heart.