warren and the lady at the camp ground

Actually, John (the husband)just went out to get some more beer and he, Vickie and Warren had been having beer along with dinner. Notice the empty beer cans along with the dirty dishes. John probably figured he'd only be gone for a few minutes. As for Warren and Vickie alone in the trailer after John stepped out, it was not very long. As viewers, we get involved in watching the scene but realistically, I would hazard to say that the time from when John stepped out to the time when Vickie throws Warren out of the trailer after he made a drunken pass at her probably was only about five to ten minutes. Hence, John was not out very long. In fact, when Warren flees back to his trailer and quickly drives out of the trailer park, we see John walking to HIS trailer. Also, he seemed to notice that Warren was driving away in his trailer so I imagine he wondered what must have happened.