For your generosity to be taken advantage of by this guy, you have to first think you are offering him something that is yours to give and wouldn't be available to him without your offer.
In other words you have to think of your GF as a belonging you possess that can be lent out or denied access to someone else by your say so.
When you mention having your GF talk to women you have interest in, you speak of it as an act she does to just let them know you're not operating with deceit. To ease their minds enough to let you have access to them without guilt. It seems as if it is not even part of the equation to you that she is giving them permission to use something that belongs to her. Neither do you seem to consider if these women see HER as a tool when you ask her to do this.
The more you talk the less it seems you think of women as people in any of this.