Re: HPV Ethics: could really use some input
First, only you can decide who you are comfortable having sex with and why. So if you are no longer comfortable having sex with her, then that's that.
Second, there's no way to tell who was the first carrier, and pointing fingers at her and producing odds is unfair. I have only ever slept with two men, both of whom were tested before we were intimate and were negative for (testable) STDs. We were in committed relationships, were careful, used protection, and I still wound up positive for high-risk HPV this January. I had the negative reaction and blamed my recent ex, and it took me a while to realize just how unfair that is--HPV can lie dormant in the system for years. There is no telling where or when it came from.
Do you have an obligation to tell future partners that you have been exposed to HPV? Doctors will apparently say that no, you do not. I think YES. Consider this: Would you have wanted to know what you were getting into before you chose to have sex with this woman? Would it have changed your decision to sleep with her? Don't other people have the right to make that same decision for their own health?
What type of HPV does your girlfriend have? High-risk strains of HPV can be very dangerous for women, and it becomes even more imperative (in my opinion) that you inform future partners of your exposure so they can know they may be putting themselves at risk for cancer.
There's no sense in martyring yourself and being abstinent the rest of your life. As you said, this is spread easily and is a common disease. The best you can do is be honest with future partners.