What speaks in favor of its being a delusion?

At the first glance, her resistance.

But I never supposed for a moment that she would not resist. I fancy
to myself any other married woman, desperately in love with another
man; can one suppose she would not resist and struggle against it and
the loved one, until her strength gave way? Resistance is not the
outcome of love, but since those two forces can exist side by side
like two birds in a nest, one does not exclude the other.

I write this diary not only because it has become my second nature, my
passion, not only because it gives an outlet for my pent-up feelings,
but still more because it gives me a clear view and keeps account of
all that is passing. I read over again the pages where I have written
down my and Aniela's history from the time of my arrival at Ploszow.
I have taken note of well-nigh every glance, every smile and tear,
caught every tremor of her heart; and no! I do not deceive myself, the
analysis is not wrong! Hers were the tears, the words, the glances and
smiles of a woman--maybe unhappy--but not indifferent. I must have
influenced her, made an impression upon her. I am not blind; it tears
my heart day after day to see how her face is getting smaller, the
hands more transparent--and it makes my hair stand on end to think she
is paying out her life in this struggle. But all these are invincible
proofs. Her heart, her thoughts belong to me. For that very reason she
is unhappy--perhaps even more unhappy than I.

I read over what I wrote a moment ago,--that I did not even suppose
she would not resist. I thought so soon after my return to Ploszow,
but lately and when she was at Warsaw I fancied that I saw signs of
yielding. I was wrong. She did not give way in the least, showed no
sign of pity; my words to which she would not even listen seemed
blasphemy to her. I saw in her eyes sparks of anger and resentment;
she tore away her hands I covered with kisses, and the words: "You
insult me!" were continually on her lips. Her energy daunted me the
more as I had least expected such an explosion of wrath. Ah me! She
threatened to leave the carriage and go on foot in the pelting rain
to Ploszow. The word "divorce" acted upon her as a red-hot iron. I
obtained nothing, nothing, nothing with all my eloquence and audacity;
neither my entreaties nor my love moved her; she took everything as an
insult to her womanhood, spurned my love and trampled on it. To-day