And furthermore, she didn't get into his apartment in the middle of the night. She was sleeping there. He knew she was sleeping there. As such, he should have expected she could be using the restroom.
I will admit, the intruder story sounded a whole lot better when it was initially speculated that she snuck into the apartment to surprise him. Having her already there and not even investigating or questioning the noise to wonder if it was his GF going to the bathroom really makes it look bad.
I thought of perhaps it really did go down as he said, but he wasn't of a rational mind to think rational thoughts (steroids), thus not bothering to check the GF and going shooting in a steroids-induced rage.
I guess what I'm saying I don't dismiss the fact that he never 'intentionally' meant to harm Reeva based on what we know. It wouldn't make him any less guilty of murder though.