eat away

verb3

1. •
   To physically corrode or erode (something) gradually.

   • The river bank had been eaten away over the years by the flood water.
2. •
   (figurative) To destroy (something) gradually by an ongoing process.

   • At your Table I vvill proue / If I can eate avvay my loue. — 1602
3. •
   (figurative) Chiefly followed by at: of a circumstance, incident, etc.: to cause (someone) to feel guilty, troubled, or worried; to bother (see eat away at).

   • The guilt of having lied was eating away at him.
   • Not confessing that I had stolen the money ate away at me until I could no longer sleep.