Okay, so that weird social media post on August 25 depicted her at a well known building called The Monarch, in Ogden, UT.
https://www.fox13now.com/news/local-...ogden-business
Ogden is 35 miles north of Salt Lake City, and 270 miles northwest of Moab. It's 263 miles southwest of Grand Teton National Park, so it's reasonable to pass through Ogden on the way between the two. Note that they were in Moab on August 12, and Grand Teton on August 23, so that's 11 days in between, and it's totally reasonable for them to have stopped in Ogden at some point and taken that butterfly/pumpkin pic.
However, they checked out of the Teton hotel on August 24 (though she was last seen on the 23rd, to my knowledge), which means for that picture to have been taken on August 25, they would have had to backtrack south to Ogden again. I find this unlikely, as the whole purpose of a nature road trip is to see new things, and it would have made a lot more sense to travel southeast (back towards Florida where they live) via a different route.
My guess is that they shot these pictures about a week or so before the 25th, and he used that as a post to indicate she was still alive -- perhaps trying to set up some narrative where she left him much later in the trip, and that she just left him at some point and vanished somehow.
I'd love to know if they were seen together on August 13. They were definitely seen together on August 23, but the 13th was just a day after their big fight, and the police had her stay in the van, while they had him check into a room for the night. If they stayed separated for a full day, perhaps the dude freaked out and went and randomly murdered those lesbians at a campsite, came back and told her, and she was on edge the next 10 days, until he finally killed her because he thought she wouldn't keep quiet about it. I'm guessing her August 19 post was done under pressure by him, but she was told not to use a location, in case the police were looking for them.
That's my working theory right now.