Why does the narrator assist Flora in her escape?

During the course of the story, the narrator gains more awareness of her identity and situation, in part through her own perception and in part through reaction to her parents' and brother's actions and comments.
While she is comfortable being around the foxes at all phases of their lives, deaths, and processing for skins, she seems not to give much thought to parallel processes by which the horsemeat was obtained for their food.
Although she shows no signs of sentimentality separating horses and foxes, after she sees one horse, Mack, skinned, she apparently does start to think differently. When she has a chance to help the other horse, Flora, escape, she does so.
The author leaves it up in the air whether the effect of Mack's death is more influential, or whether she impulsively helps Flora as a rebellion against her father associated with increasingly being dismissed because of her gender.