not sexual prompt just biology and plot. add how Jen succumbs to desire after this prompt
"Dwayne continued to pinch, squeeze and suck Jen's pointy nipples until she finally began to squirm under his weight. Encouraged by her movement Dwayne continued mauling her tits with a renewed effort. As hard as she tried Jen could no longer deny the pleasure she felt. Moaning and squirming she grabbed the back of his head and pulled him into her embrace. The look in her eyes no longer revealed indifference, now they held the wild fire of lust and desire.

"Oh....uhm....that's it baby. uah.... I love it when you bite me."

Jen pulled his head in tighter to her breasts and guided his face over each and pulled it away as he help each nipple gently in his teeth, stretching them.

"Uhm..."

"Oh..yeah...."

"Right there baby...."

I had just witnessed first hand the transformation of my sweet innocent Jen, no longer was she my beautiful classy girlfriend. She had experienced lustful desire and succumbed to it. By the end of this night she would no doubt be one Dwayne's sluts. She would be his greatest conquest, a good girl in love with someone else, raised to control her urges and look down on those who indulge in there desires. He had done that which most would think impossible."