I made a plan to steal this girls pen back in middle school
Was stealing what you wanted, or her attention?
I wanted her attention, perhaps, but also enjoyed stealing the pen.
You shouldn't steal people's things. It's wrong to steal pens. You should say sorry to that girl for the past.
I'm not going to give it back right now. It's mine now. It doesn't matter who owns it.
I think she feels violated and if you want her attention, you need to make amends for your actions.