Money really does bring out the shittiest sides of people. I had a friend do it to me where I was the one who "owed" money.
I drove us to go out somewhere and asked to borrow something like £2.30 for the car park, given that I paid for her food, I figured it wasn't a big deal. Couple of months later she says "Oh, you still owe me £2.30", I was confused where this specific amount had come from, she said "yeah on this date you borrowed £2.30 to pay for the car park".
Basically told her if she's going to be that petty over insignificant amounts of money, she can not bother talking to me again, and so I don't.