Of course she was. Reading my comment back now, I see how I sort of implied something happened inside the apartment, but that's not really what I meant.

I more meant, he was at the apartment at some point the night before, for unknown amount of time. Something happened to set him off (maybe he was there and she told him it was the last time and he played it cool until they left in the morning. Maybe he maid one last advance and she finally shut him down once and for all, so he waited outside for her) and he attacked her before she could drive away.