Never pays, never initiates kissing/sex, but good long term potential

There are two possible scenarios going on here. 1: She is an extremely private lover which would explain the lack of PDA while she responds in private. If you are willing to live with it then be patient and see how things go. If not then make your feelings be heard and let her know that it concerns you. 2: this part actually has two possibilities but all comes down to the same thing, shes hiding you. The reasons may vary from shes seeing someone else, your personal style in contrast to hers (I dont know what you look like so I have to draw reference to that) your actions in public, her reputation in the community and the list goes on. To deal with this is not to be sneaky or anything. You approach her head on and ask her simply "whats going on here"? She responds in a defensive manner, watch your back you might have a loose one. If shes willing to give you an explanation and is willing to work on it, then you got a keeper. Its a late response but I hope this helps if not you but who ever sees it.

Many women women of her age and older do not like PDA's. When you're young PDA's are racy and exciting. But that soon wears off for the vast majority of women. She responses well to your advances in private, where the real actions is, so she obviously likes you a lot. The lack of PDA's just means she doesn't want to act like a kid any more (which is understandable and probably a good thing, don't you think?).