It's 4am here so excuse me if I've recalled incorrectly, but didn't OP claim to have said he had advised his cousin to not drive out to OP's place in his new vehicle? Was it on the calls from the 13th when that was supposed to have happened?
Why would a young man spend time(20+-? mins) talking to a male cousin instead of trying to sex up his hot new gf the night before Valentine's Day, unless it was all just a publicity stunt for both of them? The usual reason you would think, given his "******" morning news, would probably be money woes, but perhaps it had something to do with OP's feud with ST's millionaire and Batchelor?
He had had stitches previously due to his inability to let his previous ex go without a fight, even though he was already in a new public relationship, perhaps there had been some ongoing tit for tat going on that OP was scared might be coming "home" to roost that he was having his cousin help him with(weren't his cousins acting as bodyguards during the trial too?)? Heck, the whole JE thing could easily have stirred up some bad blood and not just between OP and RS, wasn't JE engaged to someone else at the time that OP may have been concerned about?
So looking at possible reasons for an argument, if OP was feeling guilty for whatever was going on between him and JE, then add to that RS's coffee with her ex, then the possible news that his lawsuit over the assault charges was still a problem and maybe even getting word that he might be getting dropped as a sponsor for whatever reason(poor loser, etc) and then to have RS with her new contract and a new tv show about to kick off(even if they weren't in a "real" relationship, the brand trumps all it seems and that wouldn't be good for his).... let's just say that A type personalities don't often do well in second place, it's black and white to them, win or lose.