I can relate with the "flip being switched" situation - I can and often freely give out my time, assistance, and loyalty. I'm like a puppy who is eager to please. But if someone makes an accusation that I wronged them when I've gone out of my way for them, it can be hard for me to forgive. And prefacing the accusation with something like "I know you're a stand-up guy and you've done X, Y, Z for me/us" in some ways makes it worse, because if you're doubting me over something relatively minor when we've otherwise had a good relationship that you recognize has been valuable to you, I'm sorry, but I can't trust you.
Of course, how things are worded plays a part too. Asking me if I had put a lunch on a tab on a certain day from several months ago and forgotten to pay it was probably not the best way to approach things. I had never put things on tab and I wrote a rather colorful email making that clear. And several days later, I got a copy of a statement showing a charge to my card from that restaurant on that day, for that amount. You best I sent a "I told you so" email. In hindsight, probably not the best move, as that kind of destroyed the relationship. But in my mind, the relationship had already been broken the moment I was wrongfully (erroneously) accused of walking away from an unpaid tab of a very trivial amount.
I have been in a very similar situation. Sorry you dealt with it too.

You were right to end that friendship, imo.
And I agree, people wrongfully accusing me of things when I go out of my way to be honest, trustworthy, responsible, and empathetic… that makes me want to terminate a friendship.
Same goes for people starting intentional drama (I’ve used the “acting like their lives are a reality tv show” analogy), backstabbing me, lying about me, stealing, using me financially, and meddling in my relationships and turning people against me.
All of these things have been done to me, by people claiming that they were my friends

I think it would be really dumb of me to NOT have reservations about trusting or wanting to be friends with people, after all that
