It was a rejection of her belief that all she needs is a faceless 'presence' she's never met. For me, it wasn't about 'completing the game' ('reaching the ending'), but trying to get her to realize that the situation was horribly wrong, and to stop for a second and evaluate if there's any better ways for her to be happy.
Removing her character file from the game directory was the only thing that made her understand the player wasn't exactly thrilled about them - or Monika - being 'captive' in the space room. There was nothing else that could be done to communicate to her, 'No, this isn't how healthy relationships start', 'I'm not your salvation or someone to be worshiped', or, 'It doesn't have to be like this.' Quitting the game multiple times didn't get through to her (she seemed to be in denial about the frequent quits). txt in the game directory after noticing her attempts at reaching out through the same method. She didn't react during Act 2 when I added a. It's the only agency I / the player had left to try conveying any sort of unhappiness with the situation.
Assuming 'I didn't - I just moved it' isn't an option, or, 'I had a backup copy'.
