Angelina
Yes,your case was very complex,due to the fact you were not supposed to date at this time;good your father accepted to change the rule.
It makes sense you should show it to her before starting to date;no need to change the rule if she doesn't want dating someone wearing chastity devices.
It is a classical argument from parents;if someone truely love us(or,at least,want to date us),he/she would accept our chastity devices;if not,it is he/she only wanted sex(I don't think it is always true,but it can easily be the case too).