How would you respond, say, if you felt obligated for a promotion but didn't get one after three years?

Everything happens, in my opinion, for a purpose. I would never suspect foul play if I thought I had earned a promotion and didn't receive it. I would take stock of who I am and what I have accomplished, then focus on the good aspects. To find out where I stand, I would also request a performance review from my supervisor. I could use this information to identify my areas for improvement.