At the time, the game acted like I had her with me in dialogue before the boss fight and then after I lost, the game still acted like she was there during the bad end. So I dunno.
I never met her in my first run. I went in, retrieved the warehouse key, no succubus pair fight happened (IIRC I moved through the lower route between crates I think), I used the key, I navigated the warehouse (also pushed the boxes into place while there) and got to the boss, who I got to and then saw the bad end.