You answered me with no pretense
I checked the definition but I still don't really get it. What would be another way of saying this?
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Analysis of literature is off-topic, but...
Any of those might do, but the first is most likely. Synonyms might be guile, deception, deceit, untruth, feigning, insincerity...
One reason this sort of thing is off-topic is because metre and rhyme can force language into unnatural contortions; here, using pretense is necessary to rhyme with defense, but either it's not really the best word because it's so vague and it's difficult to know what the author meant, or it's exactly the right word because it's so vague and it's difficult to know what the author meant.
Let me rephrase it:
It must have hurt him while its said in the above verse: "I spoke to you in cautious tones" and he means here she has oppositely answered with no caution and probably frankly.
Check the definition from here. Checking Merriam-Webster for this word may not easily lead you to the answer you need!