JA was all about her image and reputation when it came to interacting with others, and she saw no other purpose in such interaction then to manipulate others to her advantage, either to get something specific that she wanted at the time, or to maintain and enhance her positive image and reputation which would alone allow her the widest possible latitude in her movements among people to eventually get what she wanted from them.
Her attempts to manipulate Travis into marriage through sex failed. In that process she revealed much to him about herself that was incongruous with the image it was so important for her to maintain. Her failure meant that an autonomous Travis would have been a direct threat, and from a credible source, to the image that was crucial
for her to maintain. IMO there was no emotional rage and Travis' murder did not arise out of any kind of deep psychic wound, no matter how pathological. It was, to her, a calculated practical consequence of the present situation, the next data point on a curve she had neither the desire nor felt the need to veer from.