'She' as sentence object [duplicate]

In the following sentence from Lolita, Humbert Humbert, in describing with maximum condescension the character of his new wife, states:

'I had always been aware of the possessive streak in her, but I never thought she would be so crazily jealous of anything in my life that had not been she.'

Why is it 'anything that had not been she' and not 'anything that had not been her'? I understand that 'she' is a third person pronoun and cannot function as the object of a sentence, i.e. The message was for her, not The message was for she, but I'm still unsure of its use here.

I tried to swap she with a noun, because I thought if a noun worked there, then so would her, like 'anything in my life that had not been house, or car', which obviously do not, but found that abstract nouns sort-of work?

She was so crazily jealous of anything in my life that had also inspired sadness.

Ironically, he was wearied by anything in his life that had not been work.

Or even like place nouns:

On the topic of holidays, she dismissed any suggestions that did not include Europe

These are unnatural sentences but I don't think them grammatically incorrect, and I feel like I've kept the subject/object patterns as the initial one.

Thanks as always for your valuable insights.

Solution 1:

anything in my life that had not been she.'

she is the nominative complement of "to be".

It is technically correct and stylistically means "herself".

Compare:

A: "Who is there?" B: "It is I, Greybeard."

Solution 2:

You’re right - the object case should be her rather than she.

The author is bending normal grammar for rhetorical effect, placing the emphasis on the marked word.

Solution 3:

I largely concur with @Greybeard that she is "technically correct", which I take to mean "grammatically correct but actually less natural than her". To be precise, the nominative is more formal than the accusative in this kind of usage.

It is I. (nominative: formal)

It is me. (accusative: informal)

Formal can be natural when used in a formal setting:

It is I, Thor, son of Odin. (nominative: formal, more natural)

It is me, Thor, son of Odin. (accusative: informal, less natural)

In Greybeard's context, which seems informal, Greybeard's reply It is I, Greybeard sounds either awkward or could have been uttered in a joking manner. But this does not to say that it's ungrammatical.

Therefore, the issue boils down to whether the cited text of the OP is in a formal or informal setting. The text sounds like a first person narrative by Humbert, so there shouldn't be any reason why it has to be formal. In fact, word choices such as crazily jealous give away its informal style. Then, why did the author use she instead of her?

We should realize that English was not the first language of the author, and more importantly that the author was born in 1899 and Lolita is a 1955 novel. The English as we know it is called Present-day English, which is the English that has been used since around World War II, so it's entirely possible that the author's English is not exactly the English we use today. I suspect that one aspect of the difference could be using the nominative as a predicative complement even in an informal setting.