仇あだになる

expression, godan verb (-ru)

backfire; have a harmful result

Used when an action intended to help or be positive ends up causing harm or trouble instead. Often implies an unintended negative consequence.

• 親しん切せつのつもりが仇あだになって、彼かれを怒おこらせてしまった。

  My attempt to be kind backfired and ended up making him angry.

• 過か保ほ護ごが仇あだになり、子こ供どもは自じ立りつできなくなった。

  Overprotectiveness had a harmful result, and the child became unable to be independent.