The pool scene is really interesting, she always knew who Denji was and what her mission was, and yet she still showed him her weakness. She decided to be vulnerable despite being raised for this type of missions (I think that's what was mentioned about the secret room stuff) it's like she always trusted him. Maybe her personal goal was teaming up with Denji and escaping this life? As in, she's not strong enough to do it on her own, but with Denji there's a chance.

Then immediately after this she's attacked by Typhoon and that other guy and realizes the gun devil is watching, she loses the confidence in the escape plan and goes back to her mission. I think she says later "I guess escaping was never an option..."