Pablo
I'm pretty sure you're a troll,but I'll answer,in case it would be useful to someone else.
Tell her you want to have a talk with her,and explain her what is a chastity belt and the purpose of it,then discuss it with her and be honest(telling her the good parts and the bad parts),then ask her if she would agree to wear one.Of course,she should be allowed to think about it for some time before answering it,if she doesn't want to give an answer right at the moment.And,if she refuses,you should accept her decision.
Christine Offer something valuable in return.
It could be an idea,which was used for some of the wearers here.But,as I said in another topic,it should only concern unnecessary things.