So... I've never touched my girlfriend..

Well, we accept the reality of the world with which we are presented. So although apparently you don't technicaly touch your gf, in this world and this reality you do.
It's philosophical, like the idea of Solipsism (or however you spell it) where it is believed that this world and everything that is 'real' is actually just created by your mind. You experience pain so you can expeirence happiness.
A philosipher (can't think of his name) once said "I think therefor I am" ... meaning, i know i think, so i know i exist, i don't know whether or not you think for yourself so i'm not sure if you're real or just created by my imagination.

Interesting stuff, but not overly that useful. And it's quite depressing IMO.