"The plan is that, when you're not playing with yourself, you'll lock yourself in this chastity belt. You can take the belt and the keys with you when you go. Unlock yourself as much as you like, but when you do I want you playing with yourself."
Not as bad as you'd thought. You can take it off whenever you want. Why would she have you wear it though?
"Just promise me you'll only take it off when you're stroking your dick for me? Please honey?"
You want to please her, need to please her. You need her so much, need to cum so much. You nod your head.