In fact, that is a very good place to be starting the discussion: seekers are under the mistaken impression that achieving enlightenment will remove duality. We have all felt hoped we would then feel comfort/freedom/happiness/peace (insert positive word of your choice!) from having attained it. But this is like saying that you would like for gravity to stop functioning after you have landed on the moon! Duality/Integration is a pervasive law of the Universe - perhaps THE law that underlies all others - so just because we now see it does not in any way imply that it will stop functioning!
No. What has changed is our perception. We now have come to deep understanding of Duality, how it plays out in the unfolding of Everything and how our unacceptance of it has been a source of our suffering. Furthermore, we understand that Integration, is not a source of comfort or a panacea!
Thus is beginning the FALLOUT process from the great disappointment that enlightenment will not be producing what we thought it would! This new state of perception does not give us any "special powers" or special place in the world. We aren't "better" or "above" others as our ego had hoped the entire time we would be. (The same ego that was getting caught up in whatever particular practice it was using on its quest for enlightenment!).
We also feel negative and at best mixed feelings towards the person who was our "guru" through the process. Since Guru (with a big "G") actually means the entire Universe, including all who come in our path, let me be more specific. By guru (with a little "g"), I mean the person who was holding the space for enlightenment to occur. The person who we actually sought out in the first place to guide us and who, for whatever reason, accepted the task and prescribed a practice and with whom we would have ongoing conversations.
But now we feel deceived because they never mentioned certain realities of the enlightenment process that we are only now beginning to digest. Or we feel anger because it seemed that they were simply exerting control over us the whole time! Or betrayed because we know that no practice can help with enlightenment and only exists to prove this point! We might say: "There are no gurus, so why did you become mine in the first place?!"
Let me suggest that deciding how to handle this particular relationship, post-enlightenment, is actually one of the first steps in your post-enlightenment process of the Return. Let me put this question for your consideration:
What would you do if you were to "guru" another on their enlightenment journey?
Perhaps in answering this question, you see that while it is indeed in your total power to walk away from this relationship (and your guru will never object), perhaps you you will instead develop empathy for the fundamental dualistic predicament of the guru/disciple relationship. And that the work never stops and they are also in their own continuing journey. And perhaps you will instead take the first steps towards something that was never possible before your own enlightenment: a true friendship of equals, both guru/disciples continuing the journey together.