We need to be reminded that the hour long 2 videos we saw of them is essentially only 1 hour of their life. Her own mother said it was just a normal argument. Fighting was normal in their relationship they were on and off for 7 years. Just putting it out there as a reminder.
What witnesses described and what Petito and Laundrie confirmed to officers may have been common between them, but this type of argument is not part of a healthy relationship.