newbie
Hello, as I promised I am here...
Firstly I have to say that you are the one that best know your fiance, so you have to know how many rights she gave you over her.
A chastity belt depends greatly of the approach of the girl about it, due that here there are girls that consider it as humilliating and me, for example that I think that a young girl wearing a chastity belt is a show of caressing.
If she has a negative concept, you have little chance.
In my opinion, that a husband be keyholder of her wife, it is not synonymous of misstrust, in fact if I would have notice of it, I would talk immediately, because I do not deserve a guy that misstrust on me.
For me, to be belted, is a way of be possessed for our men, and give him a big part of responsibility of the couple.
I find very nice that men wish to have us, I think it is natural, and in fact, usually, a lot of girls when there is love and trusting, do not feel bad with a boy in charge, if he makes us happy.
I am not married or in fetish world, but I think you should start to ask if she would like give you more power about her.
A thing can be a while in the night and another very different some days or hours in a belt. It can be very challenging for you and her. And it only can end well if you and she have clear idea that what do you want with a belt.
Good luck.