I saw someone mention where your gf is a ler. Perhaps offer to let her tickle you, and then switch.
If she absolutely refuses to do this, you have three options as I see it. Either enjoy your relationship with her for the other things besides tickling, ask her if she would allow you to tickle another girl outside of the relationship.
Perhaps you are best finding another girl who will indulge in your tickling fetish.
Moose consider back up sir! Find another girl to tickle... At least think about it!!
You could ask permission if you want to...
Honey since you don't want to be tickled... I know of a cute blond who is willing to
let me tickle her... do you mind since you really don't want to be tickled.
I want to not tickle you if you do not like it... Ok Honey...
Try that... If she say ok you are in business...
Dandy Jack!