That's kind of how it strikes me - he had reached a point where all he could think about was killing KB. I'd like to know if KB had ever done a late night cattle check with PF before - seems an odd time to be checking your cattle, but I'm not a rancher. Was she just along for the ride or was a second person needed to 'check'?
Or was he just looking for opportunities and chickening out?
The business about him killing her in the condo was at odds with the stories he spread around. Those stories indicated a depressed woman who had threatened suicide, had a problem with drugs/alcohol (had been to rehab recently), had been working unstable hours since rehab (implication being she still wasn't well), had threatened the baby, was possibly seeing someone else, had a sick grandmother and needed time to herself to work things out.
If PF was going to pull off a story about a runaway depressed young mother who committed suicide or was abducted or wilfully disappeared, his best bet was certainly not to kill her at the condo because obviously any disappearance is going to trigger a search that starts at home.