What are non-criminal things you consider unforgivable?

Not counting murder, rape, torture nor any other terrible criminal stuff... what things do you consider unforgivable that not even with a sincere apology helps.

I think if you went out of your way of bullying someone for your own pleasure (and you're already a lot older... not a little kid anymore) or trying to ruin people's relationships (ex: lying to them that you saw their partner cheating) that doesn't deserve any forgiveness. Unforgivable. What about you? What is unforgivable to you?
What are non-criminal things you consider unforgivable?
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