I have thought that perhaps, it's not improbable, that they stopped to speak with Lucas and Chynna, and suddenly realized that these two were precisely the reason they themselves never got along in their world, and may never get along.
Two good looking foreigners, with money to travel, love to spare, obviously having had all the advantages so far denied to K and B ( in their way of thinking ) having the nerve to travel on Canada's highways, without a care in the world, while they have to scrabble for work, and food, with no heft up by parents, etc, . All the usual stuff.
From then on, it 's been open slather, nothin' to lose, and what the hell..