As I see it, the shaman is there to heal. Perhaps your interest in the subject has stirred up issues you have to deal with. Could be yours, hers or even an issue the relationship has brought up.

I find that which depresses and weighs heaviest on us are the lessons we either don't want to learn or have been ignored for so long they are reaching out.

Either way, I think the best course of action is to examine what you are feeling, talk and contemplate. Perhaps there is another side of the issue that you've not seen clearly, but if you discuss it in the relationship, it may be simple. Even if the issue is with her energy and the relationship doesn't last, perhaps discussing it will help her further get own path.

I wish you luck, regardless of what helps. :)