He fucks his girlfriend then his stepsister wants to try

I thought making out with my stepsister would just be fun and relaxing – she’s so inexperienced and always dresses like a little girl, so I thought I should show her how to be a man, but it was just a kiss! Now she’s freaking out because I brought my girlfriend home and she won’t stop rubbing my cock with her feet under the table… in front of my girlfriend! She’s so jealous that she even dresses differently and acts like a slut. Where’s my innocent sister? There’s no way I’m not going to fuck that ass if she keeps teasing me or touching my cock one more time, which I know she will.