Vincent already now knows that it's Paula but he plays along with her act for a while. He gives significant hints to paula so that she gets that Vincent knows she's Paula but of course she doesn't get it. In the end a very significant thing happens(which makes me think she suffered so much it made her low-key schizophrenic) and Paula runs towards the hidden gate at night(fully intending to run away) where she sees her old hair ribbon tied to one of the trees then Vincent appears and says that he knew she'd run towards the gate eventually.
The reason why Vincent plays along with Paul's act isn't to tease her, rather as to not startle her but revealing it too suddenly.
We all know she's a timid little mouse with no self-confidence.
how many more chapters to this
Chat did her true identity’s revealed?