Layperson question coming up - Say a decohered particle reaches an un-decohered state outside the realms of our detection. Does this mean that for that particl

Layperson question coming up - Say a decohered particle reaches an un-decohered state outside the realms of our detection. Does this mean that for that particle time didn't elapse? As far as the particle is concerned, someone observed it and then someone was unable to observe it. This hinges on whether a decohered particle can go back to being undecohered. If the answer is that particles can stop decohering, then our status as observers is merely a contrivance for us to checkpoint a before decoherence state and a decoherence state.