Ahhh sorry, english is not my primary language so it's not easy for me to spot the nuance in this language. I apologize.
I do see your point there.
It's obvious that Negi view Asuna differently than the rest of the class and his pactio-harem girls.
She's the first girl kicking him, making a pactio, living with him ( and Konoka), going everywere he go , always pointing his errors (with Chisame afterward), conforting him when he's not okay (Chisame also for this part) etc.