Step Son

I’m trying to figure out if it is my manual or if it is a boundary I need to set. My 22-year-old stepson works 2 months of the year and makes enough money to pay the rent we charge for the rest of the year. He spends the rest of the year in his room playing video games. It’s complicated because his mom thinks he is an angel that can do no wrong and wants him to live with us forever. I want our children to grow up and leave home and have their own lives. I don’t know how to reconcile this, please give me direction.