regret
n//ɹiˈɡɹɛt//ånger, beklagande, ångra, beklaga
Emotional pain on account of something done or experienced in the past, with a wish that it had been different; a looking back with dissatisfaction or with longing.
(decision theory) The amount of avoidable loss that results from choosing the wrong action.
A person invited to an event who was unable to attend, but notified the organizer of this beforehand; a nonattendee.
To feel sorry about (a thing that has or has not happened), afterthink: to wish that a thing had not happened, that something else had happened instead.