It does, indeed, depend on the situation. We talking someone bumping into you, to being cheated on levels of difference, after all. I'm very laid back for the most part, but then, I had a hard betrayal about half way through last year, and I'm still struggling to get over it. I'm finally starting to process it properly here lately, and though I won't "forgive" until I get an apology, I'm done holding a grudge.
I'm trying to be more forgiving in life. I was resentful towards people who hurt me, like my brother, but these days I try not to let things linger because life is too short and there's too much crap already
If I think you meant well, I'll let it go quickly. If you fucked me over for your selfish purposes, I will hold it against you forever. Cause problems for me at work, and I'll make sure you aren't in a position to do so again.
Threw me under the bus as a PM? Good luck ever being the PM for anything I'm working on ever again.
Fired one of my people for BS reasons? Enjoy having no say over any personnel decisions going forward.
Try to get more than your fair share in the divorce? Whoops, somehow the paperwork has no penalty for me taking years to pay out your equity in the house.
It sometimes takes a bit of time, but I guarantee if you fuck with me, you'll regret it.
I tend to forgive too easily or assume people feel sorry for what they did because they said so or even if they didn't and learned something and aren't going to do it again, even after they've done the same thing several times. I tend to pity people who did something bad, feeling like they must have been in some worse situation to have done it. I also seem to attract an unreasonable amount of narcissistic people. Perhaps they can smell my over forgiveness.
Weirdly I'm apparently totally aware of these things, when put in charge of other people, I'm excellent at defending them against bullshit. When it applies to myself, there's some sort of "self-forgetting" that happens. Like I said elsewhere, I'm trying to learn to "be more selfish". I've started writing notes for myself to remind me of specific offenders so I'll stop forgiving them and letting them get away with things at my expense.