No doubt in my mind that's exactly what happened. All of a sudden, on the anniversary of the previous incident, they start fighting out of nowhere, making references to the incident, acting acting the same as they did in the past, and then reenact the murder-suicide? All while he's getting increasingly frequent visions of the old house and people overlayed over the current house and people?Poor kid, there's a big chance those couple got possessed and wasn't really fighting.