There are a few steps necessary to keep her. You can refer to the walkthrough (linked above) for detailed information on what you need to do.
Thank for the tip.
I finally manage to convince her to join me.I didn'y submit her, because it's my first game, and I want to play the more nicely I can.
But I have a bug in a script later when I try to talk to her (I have submit the report on Discord).
