I still keep thinking he took her keys earlier in the night, lept at the chance to give her a ride to her dads or a friends nearby, and as soon as she was done calling HF from his phone he turned is phone off so HF couldn't call back and interrupt. From there on what triggered their brawl, I don't know but it seems SA related (and probably didn't help if he had drug/alcohol in his system). Of course my theory has changed a few times with the release of more and more information. If they would release everyone's phone records, so we could see who was calling and texting who leading up to their departure from the garage, that would probably paint a much clearer picture.