My girlfriend of six months is the straitlaced type and does not care much for sex. Her older sister is her complete opposite—carefree, a little ditzy, and suddenly all over me whenever we are alone. Her raw, irresistibly erotic body, the sultry whispers in my ear, and the revealing outfits she wears to tempt me even with my girlfriend nearby are impossible to resist. We spend three days having sweaty sex, soaking each other as she squirts again and again. By the end, I am completely obsessed with her.