Stepsister or Girlfriend

I thought making out with my stepsister would just be something fun and chill she s so inexperienced and always dresses like a little girl so I figured I should show her what a man tastes like but it was only a kiss! Now she is freaking out because I brought my girlfriend home and she wont stop rubbing my cock with her feet underneath the table... in front of my girlfriend! She is so jealous that she is even dressing differently and acting like a slut. Where is my innocent little stepsis Too bad Im too weak. Theres no chance Im not going to fuck that ass if she keeps provoking me or touches my dick one more time which I know she will do.