I agree with Superjast in that this really has little or nothing to do with 'poly as such - at least yet.
But exploring sexuality between 2 or more people is always kind of opening that box. Our sexuality is a complex thing and not a lot of people are aware of that because of the lack of frank (or Frankie) discussion of sex in our culture. We talk all around the really important stuff - avoid that when possible.
And what happens ? Just as you discovered !
In a lot of cases when we discover a partners true sexual inclinations or preferences/kinks, if they don't resonate with us personally we get scared !
Are we no longer compatible ? Yikes !
In most cases, it doesn't mean that at all. Despite the new discoveries, it's highly likely that we still have mutual sexual interests/turn ons.
But what it DOES mean is that now we have to release some fear, along with some strange ideas about being the be all / end all to anyone in a sexual manner. There may be some areas of their sexuality that we either don't belong in or really aren't comfortable in.
And that perfectly OK !! Really. It is.
But we're not taught that and don't talk about it. But if you can get over that wall you actually reach a whole new higher level of connection with that person. You become a partner in helping them explore who they really are at a core level. And that type of sharing in most cases, if it's genuine, moves a relationship to a whole new level.
So I suggest being open minded and partnering with her in her explorations. As hopefully she will in your direction !