I find it interesting that many people try to invalidate the feeling of being friendzone. I find it as a natural biological reaction to not getting the relationship one wants.
That being said, I think the best way to deal with being friendzoned is to be honest about one's feelings and end the friendship. No use in being around people if it makes one bitter.
It is annoying. Because when I was single, into a guy friend who was not into me, the only sane reaction was to say to yourself "it sux move over". It was 100% not blaming him or acting like he has done something wrong. Anything else would be being crazy.
Friendzone is not something mean a girl do to you. It is her not wanting to date you. Don't pretend friendship if you are not actually interested in friendship.