I took a virgin (STRICT) Mormon girl who would blush and tell you not to be crude if you used the WORD "sex" in a sentence, let alone talk about the topic itself and turned her into a total sexaholic nympho. It can happen. It takes time- it takes PATIENCE- it takes understanding (and in my case, actual love
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). Go slow. TALK. Really.
In your case, she most likely was taught at an early age that sex is bad, it's dirty, etc., more specifically that sex purely for pleasure and not for procreation (read: religious nuts) was wrong or bad or dirty or slutty, etc.