Mijn stiefzus geniet meer van seks met mij dan met haar vriendje

My stepsister complains all the time that her boyfriend doesn't know how to touch her or make her wet. She also says that she doesn't enjoy when he kisses her because, apparently, he doesn't know how to kiss. So my stepsister turns to me to satisfy her carnal desires, since I know her body very well and I make her reach the stars, like in this video.