I want to ruin my ex boyfriend's relationship. I want to make them end it.
What makes you want to ruin your ex's relationship?
I am really in love with him. And his girlfriend is stupid.
I'm sorry you're stuck on the guy.  But you need to move on, as dwelling on past relationships as much as you are is pretty unhealthy.  You'll find someone new, I promise!
I wish my boyfriend would come back to me.
You will find someone new who you like. It's going to happen for you and you need to move on from your ex.