I don't usually engage in wild speculation but one thing I have thought Oscar might be hiding is the full circumstances of when they woke up. He testified he had asked Reeva to close up the room and bring the fans in before she fell asleep (presumably he anticipated falling asleep first? Dunno.) Based on some past behaviour I can imagine Oscar waking up annoyed at her and being snarky and huffy. This would have made Reeva's silent exit of the room and the kind of wordlessness between them necessary for Oscar's version somewhat more likely.