IMHO if you are trying to figure out why JA brutally and viciously murdered TA using logic and reasoning, then you are doing it wrong. While I agree there were definite steps taken that constitute premeditation, I don't believe those steps were taken as the result of a logical, sensible mindset capable of predicting cause and effect.
JA and TA had a complicated relationship that went through phases and evolved over time. The consistent through-line was sexual, and that's where I think JA started confusing violence/aggression and sexuality/physical intimacy. (No, not a sexual amnesia or whatever Samuels was talking about.) I think that JA fully bought into the double standard that somehow her sexual nature and sexual activities with TA reflected negatively on her, (as a woman,) in a way they did not reflect on TA. I believe that TA promoted that idea and was attempting to rid himself of her by shaming her for her sexuality at the same time he was enjoying her availability.
I'm not interested in a religious debate, but I've heard JA use the term "courting" (courtship,) which has a specific meaning in fundamentalist christian circles. While JA may have aspired to being courted and being a good Mormon and being in the "in crowd," she must have come to the realization ultimately that she instead had lost all self-respect. As a feminist I know many women, myself included, who have had to work through issues of self-identity as it relates to sexuality. JA made the decision to destroy TA as an object of her own self-hatred. After all, TA was going, (or had gone,) to the Bishop to begin the process of repentance and coming back into the Mormon fold. That was not an option open to JA without exposing her sexuality to the scrutiny of others, a much more dangerous prospect likely to arouse condemnation and disgust. (And she is one who, according to Ryan Burns, was socially awkward even in amongst other PPL folks whom she knew well.)
As another poster pointed out in a thread long gone, JA was jealous of TA's success; financial, interpersonal, material, familial, spiritual, all of it. I believe she killed him as the only means she could see to pull herself up from the bottom of the barrel, from depravity, from self-loathing. I believe she wanted power over him, to control him, to have the last word, to inflict as much pain as possible. I don't believe she was mad about any one thing; Cancun, the other women, being called a *advertiser censored*, *nal sex. The paradox of JA's actions is that she killed TA to bury all the "bad" in herself, but instead she uncovered it for all the world to see.
