Regret
Regret, for me is something which someone can't cope with or without the encourage to face.
Even if I have done something wrong, I will try my best to correct, to rectify, to change it from so called "wrong" to so called "right", if fail, shall let it go, why do we need to regret for something which is irreversible? I don't know...
Maybe we regret to self punish on what we have done, or trying to victimise ourselves to get the mercy from others, I don't know.
What's regret? I don't know...