A girl who exudes purity will not elicit that persistance from a man.
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In addition to the girl's personal virtue, her support group (or lackthereof) plays, I think, a huge moderating role in whether she rejects the advances of a man.
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Women are almost completely hopeless when it comes to standing on principle and doing anything that would earn the disapproval of someone else.
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If a girl has an active and present set of family and friends who would disapprove of her behavior, I think that makes it a lot less likely she'll fall into these kinds of sins.