Okay, so she gets into the bath with him to demonstrate good faith and to acclimate herself to something she clearly finds difficult. She tells him that this (the act of sitting naked together without touching) is all she can manage at present, as a first step. It seems like a pretty sweet and generous gesture, tbh. All she asks is that he respect her boundaries and treat her with respect.
He proceeds to leeringly molest her despite her repeated pleas that he stop until she's finally left cowering in tears. He's coldly arrogant, condescending and demeaning throughout, announcing that he knows her better than she knows herself and clearly not caring at all about what she says or feels. It's basically a rape scene that stops short of penetration.
I get that this is a woman's submissive/masochistic sex fantasy about being dominated by a cruelly sadistic male master. The tropes are familiar to me from countless of other, similar stories. As a male reader, however, I still find scenes like this more infuriating than arousing.