To leave or not to leave

I had a particularly bad day at work and really wondering about the wisdom of staying in a job that that is so unsatisfactory. I love my profession, I strongly believe in the values of libraries and have devoted a huge part of my life to it but it comes to a point when you have to cut your losses.. On paper I have an excellent job, which makes the decision difficult. In practice there are many aspects which drive me crazy and I feel I am not being allowed to work to the standard I would like to. It might improve... or not. I may never find as good a job. I am being unreasonable and wanting to much? Should I stay or should I go?
Anyway I needed that glass of wine...