The only time something would become unforgivable is if it were done with intentional malice or becomes a pattern of behavior. I’m willing to forgive quiet a bit, if the harm an action caused was not the intent. When it becomes the intent, such as physical violence or repeated trauma, that’s where I take a hard line and will not forgive. For less spectacular transgressions, repeat events are where things become unforgivable. I am willing to give grace on that more because I’m bad about not communicating to others how their actions hurt me, but if we’ve talked about how their behavior is a problem and they keep doing it? No sorry, we’re done.