Betrayal.

Some times you go out of your way to get someone's back when there's a rough situation, and you have the presence of mind outside your own head to realize a person might have their back against a wall, feel lonely, feel confused, and you do what you can to comfort that person. Drop your own misery for a bit and reach out, if just to tell the person you're there and available, that not everyone has abandoned them. Even when you've had your own issues with this person in the past, you overlook them because you hate to see a soul in pain.

And then sometimes these same people weeks later turn their back on you, spit vitriol or just ignorance at you, and stare with beady blank eyes into your face letting you know they're back to being the same closed-minded, control obsessed dickheads that keeps them isolated and disliked in the first place.