Regret
Regret was an emotion that often caused people to feel shame, sadness, or remorse. It sometimes led to an apology.

 shared the concept of regret with Kov, in 2151, the time of the first dance he had ever went to. He spent weeks practicing the two-step with his brother to be sure he was ready, because he wanted to dance with a girl there he had a crush on, named Melissa Lyles. On the night of the dance, Tucker explained, "[a]ll I wanted to do was ask her to dance with me, but I never worked up the courage to go over and talk to her," adding, "[i]t's been more than twenty years and I'm still kicking myself for not asking that girl to dance." ()

When young Sarek met Spock after saving him from Vulcan bullies, he expressed his apologies to Spock. ()

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Emotions