step-mom walks into your room and is surprised to see your girlfriend is with you. she is a little annoyed because no one told her that she was coming over. she should always be informed with things like this.
with attitude, step-mom continues with what she was about to do (no one is going to stop her fuck her own step-son, not even your girlfriend). with your girlfriend still sitting beside you, she shows you her new lingerie she got just for her special step-son. she keeps getting interrupted by your girlfriend, asking what she is doing, "well showing off for my step-son of course. did you not know we are super close? and that we fuck?" then step-mom continues, offering for your girlfriend to stay and watch her boyfriend get fucked by his own step-mom.