She'll be in charge

"I'll be in charge, essentially. The two of you won't be allowed to do anything unless I allow it. Even if he comes up to you, hard and ready, you have to ask me, and if I say no, you have to accept it."

"So basically instead of me denying him it'll be you?"

"Ah, you noticed. This will prevent the strain that having you denying him could have on your relationship."

"Sounds like a perfect system, but how do you keep me from breaking it? What if we have sex, and just don't tell you about it?"