When you're between a groomer and abuser and liar and St Rivers
oh boy I seem to have touched a nerve
so, I agree with none of these assessments of Rochester except "liar." the internet seems to have forgotten this, but grooming means conditioning someone to accept (in this case) otherwise unwanted romantic and/or sexual advances.
is it weird that Jane is 18 and Rochester's 40? very much so! even within the text people comment on it! but their romance is definitely not grooming. they have some fairly normal conversations and then she's madly in love with him. (and if you mean grooming in the even move common internet sense exclusively implying child abuse, Jane is very much acting as an adult within her society, albeit a young one. there were average age gaps back then, but there were not the social barriers between New Adults and Older Adults that we have now. you were just Not An Adult and then An Adult, end of)
as for abuse, if you're talking about Bertha...taking the text at face value, he doesn't do wrong by her, IMO. she has Incurable Violent Psychosis of Never Coming Back From this Ever. medications are not a thing. therapy is not a thing. divorce can only be obtained in cases of infidelity, and if HE wanted to sue for divorce, he'd have to prove that SHE had been unfaithful. which she is seemingly incapable of doing because, again, she recognizes no-one and is not lucid
he has two options: keep her at home or send her to an asylum. now, an early 19th century asylum COULD be fine and try to help her, contrary to popular belief. but it could also be abusive. and one might not know just upon going to view the place as a prospective "client," because they'd try t put their best foot forward
so he engages her a nurse. he gives her comfortable rooms and good food. he locks her in, but she is amply proven to be a danger to others (and herself, since she eventually commits suicide during the fire), so that seems unfortunately prudent. and I don't really see how he could do better under the circumstances
now, how the text handles Bertha, Doylist-style, is HIGHLY open to criticism, through lenses of racism and ableism and more. Mr. Rochester and Bertha are not people; they are characters, and they reflect the author's deeply flawed ideas about race, mental illness, culpability in marriage to a spouse whose mental state deteriorates, and more. but again, taking it at face value, I don't think he does abuse her
obviously he lies. the guy tries to marry a woman without telling her he's already married. that's a pretty huge transgression. and before that he tries to make her jealous by pretending to be engaged to another woman. but it's a Gothic novel, so...par for the course
whereas St. John is actively shitty to Jane. you want to talk abuse? try "forces a woman to abandon her own wishes and plans and do what he wants, tells her she's not made to be loved, tries to use religious coercion to override her refusal of his marriage proposal, tells her she's going to hell if she doesn't marry him, at times straight-up says that yes she will marry him actually, and is generally such a stifling and controlling douchebag that she thinks marriage to him might actually kill her and his own sisters tell her not to do it."
Rochester has many, many issues, but as a potential love interest for Jane, yeah, I do think St. John is worse