“Disappointment and hurt are feelings that don't go away easily. An apology alone often does not heal them.”
Related quotes

“Don't ask permission. If it does not work, you can apologize later.”
“Nothing heals the soul like chocolate… It's God's apology for broccoli.”
Variant: Chocolate is God's apology for brocolli
Source: The Sunflower

“Does pain go away and leave no trace, then?’
‘You sometimes even feel sentimental for it.”
Source: Thousand Cranes