I have long pondered possible/likely scenarios which would result in the crime and I have also come to a similar conclusion.
It is based upon previous experience, human nature, past behaviours, character studies, logic and the limited evidence.
I do think that the evening of Feb 13th was a major row and it had been brewing for a few weeks. It escalated to a new level though there had been signs that threats and violent bursts of anger were possible, likely not directed at RS herself until that night but at objects or excessive speeding, other signs of a dangerous temper and loss of self control.
For whatever reason, the actual triggers for this major row are private - no known evidence at this point (relationships are not catalogued perfectly and chronologically in media and software data, especially someone like OP who has already stated that he prefers to talk in person or by phone).
The trigger is extremely likely to be jealousy, possibly exacerbated by unknown personal, financial or relationship issues. It escalated into a dangerous and physical confrontation, mostly upstairs (damage to bedroom door) and OP feared the repurcussions this time as he'd gone much further than previous flash points, both in this and previous relationships.
It was the end, not just another OP tantrum but this time a life changing event. He panicked, totally flipped and kept RS captive in the bathroom area (much damage, jeans out of window) for a period of up to 1 hour after 2am.
I believe that it was him who forced her into the toilet and separated her from her phone which was the biggest threat to OP at that point. He was only killing time for the moment.
He tormented her, threatened her and this continued berating and humiliation ultimately ended in a complete loss of control due to her continued petrified screaming (fear of alerting neighbours) and he murdered her in cold-blood at around 3am.
His mythical intruder story may even have been invented and planned during that final traumatic hour and perhaps was the final bit of madness/confidence to take out all his anger, fulfil a thrill seeking gun nuts wet dream and fire those four shots through the door into his now ex-girlfriend.
I was also wondering initially if she may have been locked in the toilet for a long time until I read Mrs Stipp's statement again yesterday .
She said she had heard screaming for a while and then the screaming got louder so much so she thought someone must be running down the road towards them My guess is the first screaming she heard was by the bedroom doors and that when they were being broken down Reeva then ran screaming to the toilet .
One thing I am struggling to figure out is why Reeva didn't actually make a call to anyone if she had her phone with her . Either she didn't have a signal in the toilet or it was never in the toilet .
The other thing is although Reeva was screaming I don't think she ever saw the gun and thought he was actually going to shoot her because I can't believe that she would just be stood behind the door so it certainly seems cold blooded .
If she was expecting him to shoot at her I think she would have crouched down ,stood behind the wall (at the left hand side of the wc ) unless of course she didn't have time and he shot her as soon as she locked the door .
I will have to go and re read Mrs Stipp's testimony again ( for about the 4th
time ) to check timescales of screaming after the movement she described .
I know OP believes we will accept his statement that it was him that was screaming but I am pretty sure Mrs stipp's said she heard a man screaming when tests were done before the trial started.
Another quick thing I noticed yesterday.
I and a couple of other FM have suggested in a previous thread was that he had aimed at Reeva from her voice . The consensus was this wasn't the case . I felt it was because all of the bullets were all shot into the left hand side of the toilet.
Anyway I was reading the bail/charge documents again yesterday and noticed that the state also believe that he was aiming towards the basin (toilet ) and said so in that statement . Hadn't noticed that before and yet had formed that opinion anyway. It was the overhead photo that the state Ballistics guy took that made me think so .Why would he be doing that ?
I have a feeling this will be another point that Nel will put to OP .