As a human in our day to day personal lives, it's easy to get into an accelerating loop of resentment.
In general, if you're actively looking for things to resent, you'll find no shortage.
The world is noisy and ambiguous.
There's always a shadow to interpret maliciously.
One of the cycles of escalating tensions in human systems: if you think you've been aggrieved you think you're justified in hitting back.
But the perception of who has been aggrieved and for what is something where you implicitly think you're special, and so you overweight things that have happened to you and underweight things that happen to others.
So the other person sees an escalation, and responds to the over-reaction and that accelerates in a loop.
When you hold yourself to an impossible standard (e.g. perfectionism) and then fail, your ego will need to find an external cause to make it so it's not your fault.
That external cause will both justify your failure, and your intense emotions you feel about the failure.
"I have found the villain and it's this other person."
This can create a spiral of self-sabotage.
You justify bad behavior by inducing others to do things you're justified in behaving badly in response to.
A toxic spiral that tears down not just yourself, but others around you.
The way out of this loop? Having compassion for yourself and others.
"I'm not perfect, and I never will be because that's impossible. But I'm good and I can become better with intentional effort. This is true for everyone, not just me."