I think those are signs of burnout. Eventually, it can drive anyone to resign. Wala ng sense of fulfillment eh. Personally, I only leave a company for one of two reasons: I'm not happy with what I'm doing anymore, or I don't believe in the same things anymore.
A friend of mine told me naman that the only reason you should leave a company is because you are offered a better opportunity elsewhere. It doesn't have to be monetary. Pwedeng mas fulfilling, o kaya e katuparan ng mga pangarap mo, like starting a family. Kasi daw, hindi pwedeng when you feel the same things again, ganun ulit. It only becomes a vicious cycle.