regret

noun
  1. A feeling of sadness, repentance, or disappointment over something that has happened or been done. noun
    She expressed deep regret for her harsh words.
    He felt regret after missing the opportunity to apologize.
  2. To feel sad, repentant, or disappointed over something that one has done or failed to do. verb
    I regret not spending more time with my family.
    She regrets her decision to leave the company.