In the first place, "Nicholas II" is an acceptable answer to the question posed by the thread, and it was given almost as soon as the thread started. You can disagree with it, but you cannot rule it out at this point. If you disagree with the answer, why not try and explain why?
Okay. This point was taken back on page one and is taken, again, over here on this page.
This topic is being discussed over on threads created just for your topic.
Now, ON THIS THREAD, let's discuss people who betrayed their Tsar Nicholas II.
In the second place, define "betrayal" in such a way that it can be answered within the parameters of your question. Do you mean who broke an oath to the Tsar? It then becomes proper to discuss what is an oath, and how much strain can it be subjected to before it loses potency.
I believe some have discussed the oath to their Tsar. So, who gave this oath and broke their oath?
I gave an example from the Memories of Count Paul Beckendorff where the troops continued to protect the Tsar and his family even though they were no longer bound to their oath since their Nicholas II was an ex-Tsar because he had abdicated so they had been released.
If you wish to say that he was betrayed by everyone who thought he should abdicate, or by everyone who thought he was incompetent, or by . . . . well, I think it is obvious. Start another thread with a more precise understanding of what it is you are trying to determine. You may not arrive in the middle of a discussion and announce that you are making up the rules to suit yourself if they weren't clearly defined at the beginning.
If you wish to go to the extreme of using the telephone book and naming everyone who betrayed Nicholas II, that is your choice. However, for the sake of this thread, I would prefer that we remain within the boundaries of those people who were important in the Tsar's life and it was their choices which made a huge and very serious impact upon the Nicholas II's future as Tsar.
As for making up the rules, you can start your own thread about how this wooly headed bear can climb a ladder...... to fetch honey

or better, yet, create the topic on "How Did Nicholas II Betrayed Himself?"
AGRBear