I don’t think he was planning on killing her during the road trip. Like Brian tells the cop and she does as well, it had been a few days of little things here and there. Basically what I think happened was that morning, he wanted to get on the road and she wanted to do some video editing or whatever and she spent like 3-4 hours at that diner or whatever it was, and he was pissed at her. She probably got irritated because in her mind, this was her project, her job now, and he was there to drive and be patient. He probably diminished her blog dreams and is why she calls him a “downer” when she is talking with the police.
what I find odd is that they had taken a trip like this before, but in a smaller vehicle, but that was when they were probably in a honeymoon phase. But this time, this had become her job.
This case will change the way Utah handles these domestic calls, now the assailant will have to sit in jail for a mandatory 24-48 hours, no more just separating people or giving them the benefit of the doubt.