Stepson girlfriend finds a way to make a move

StepSon‘s girlfriend said she wasn't feeling well so she didn't have to go hang out with my stepson and his douche bag friends. I thought she just wanted to get out of it so I just went to my room and started watching TV a few minutes later she walks in my room, but naked. She said are we gonna do this? I was confused and before I could think she had my cock in her mouth.