My own experience
My wife of 12 years was NOT ticklish when I met her. At least not on the level she is now. We worked together on her sensitivity, a trustful, light tickling, a stroking, loving feeling that built into more of a tickle. Building her sensitivity. Did she know what I was doing in the long run? She has for a few years now. And loves the feeling, but not always. I'd tickle her all the time, but she doesn't share my fetish. It's the love, man. I went with the woman I love, ticklish or not. I tried to bring out her sensitivity as best I could, for me and her, to enhance the fetish-related sex that I enjoy. Yeah, it was all for me. With added benefits for her that she never before knew existed. But she was worth it, ticklish or not. Period. And if your girl has a shut-down from a past guy, then she may be some work. And if she's worth it to you, to whatever level you can bring it to the surface, it's TRUST that will help you in the end. Not going too far, repecting her limits, playful tickling often helps if torturous tickling has preceded you. And a little light-touch goose-bump tickle strokes often melt.