I can explain on how to not lock her route first you need to select maybe a little for her first encounter..(This will now have you on the path of her success route) all this you must have charisma for most of theses to work I would say do low charisma then level it up.
Second encounter you'll need to select the bottom answer . The first answer will reduce your favorability.
The third you must pick (the first option will affect the choice if you haven't picked it. If you did pick it. You'll get that she's not tired.. this will give you an option that will increase you're favorability by 2 . you have to pick the first option for the first dialogue . You then must pick the first dialogue as well when the second box appears.
Fourth is connected to the first option. So it's important that you picked the right option.. If you picked Maybe a little, you pick the option "Is there something you'd prefer.?" from there you'll pick "would you like that." And then the options after that doesn't matter expect the last one does. Pick the option. "You two sound close.".
You'll know if you do the fifth encounter right if you see the option, "Don't hesitate to come and find me." This option requries you to have average charisma. THIS Will GUARANTEE success.