I get to have sex with my girlfriend's friend while she's on the phone with her

I've always had a thing for my girlfriend's best friend. She's a bit older and curvier than my girlfriend, but there's just something about her that drives me wild. When my girlfriend is out of town, I finally get to make my move. I sneak into her house and catch her alone. She's on the phone with my girlfriend, her voice sultry and low. I can't resist her allure any longer. I start to undress her, my hands exploring every inch of her body. She doesn't even notice at first, too absorbed in her phone conversation. But when she does, she doesn't object. In fact, she invites me to join in. We end up in a passionate encounter, our bodies entwined in a dance of desire. The whole time, my girlfriend is on the other line, oblivious to the steamy scene unfolding in her absence. It's a tantalizing taste of what it's like to be a part of their secret world.