Nah, I am not a fan of these absolute retard premises. What do you mean she acts like a total cold bitch in front of the single dude that she actually likes? How the fuck would that look like where she puts up the cutesy nice act for everyone, but just for the MC she's cold af? That's not what nervousness does to you, and that's not tsundere either. This is selective retardism. There is literally NO way the MC would think he likes her, this is ALL on her being an actual piece of shit. She does NOT get enough shit for how she is. If I was her coworker, I'd be bashing her about how much of a piece of shit she is to him and that she needs to fuck off from him, and that he deserves someone way better than her.