It's not uncommon to have conflicts with a stepchild. Unlike other friendships and relationships which grow over time, stepparents have been invited into your family by a parent and you suddenly live together.
You may feel confused, angry, or sad about the many changes that happen all at once, and that's okay. While initial changes can be hard to adjust to, realize that it can and will get better with a little effort.
I put it together for you in this book the little efforts you need to make to become a nice stepparent.