In this adult sibling role-play, my possessive older sister has always been far too attached to me. I assume she will back off once I get a girlfriend, but jealousy only drives her across the forbidden line. Knowing that my girlfriend has little sexual experience, my sister uses her mature techniques to overwhelm me. I hold out at first, but her relentless nipple teasing finally makes me surrender, and she keeps forcing orgasm after orgasm from me. After this, ordinary sex with my girlfriend may never feel the same again.