It seems that these two were unsuited for close quarters of the RV lifestyle.
Of the several people I’ve encountered with whom I have not been well suited not a single one of them has ever been murdered.
People have always tried to project their best image to others. The fashion industry, cosmetic industry and public relations industry depend entirely on that drive, so self-promotion is nothing new. Prior to social media, back when human beings interacted on a person-to-person basis, an individual actually had to provide some substance behind the image they were presenting to the world. While there may have been a gap between image vs. reality, real interaction with others usually kept that gap from getting too wide to bridge.
One problem with social media and the social media generation that I have observed is that individuals can put an image out there of happiness, success, wealth, etc. seeking affirmation from countless thousands or even millions whom they will never meet. Harvesting, "likes" on a social media account affirms the image and not the reality, to the point people begin to wholly believe in their online persona and lose touch with their true selves. In doing so, they lose their ability to interact with others in the real world where their online persona simply doesn't work.
So what does this have to do with this case? Maybe nothing.
On the other hand, the disparity between their YouTube vlog and the police video, I think, shows that in this case that gap between image and reality became irreconcilably large for this couple. The images in the YouTube video they posted were one of the happy, carefree, nomad couple out to discover the world on a worry free drive across America. The police bodycam video pretty much shows that the reality of a long road trip was probably something neither of these two was emotionally equipped to deal with, no matter how much they believed they were.
Just my $0.02.