Alright I found out why it happens. At the first scene you get the choice to help her or refuse, if you refuse it stops it, however then you get a next one which is if Juliette asks Elisabeth if she's masturbates or choose not to. IF you choose to ask if she masturbates then you're hard-locked in on the lesbian route, you don't get the hard opt-out later on in the bathtub.
Idk why it's like that, personally I think that's kind of silly but it is what it is, I guess. So if a woman asks if another woman masturbates = locked in for lesbian content.