My brother has been with her for 4 years, she seems pretty nice all round.
I've never had an issue with her and we go out for coffee every few months for a chat.
Without fail, if I owe her money, she has something to say about it. But its very small amounts of money for example, I didn't have enough 50ps for the parking ticket machine, so I asked if she had one, then bought her a coffee costing £1.50, which I didn't mind doing, as a thank you. Next time she saw me she asked for her 50p back!
Now I hardly shower her with money, but a lot of the time if we're out together I'll get us a sandwich each while we buy our own coffees, or occasionally I'll buy her coffee too. I generally am 2-3 pounds worse off for this, which is fine I wouldn't dream of keeping a tally, But I've noticed that she'll often quibble over small change, Never more than 78p (Yes she asked for it to the penny!)...
AIBU to wonder why someone would do this and AIBU to stop buying things for her? It seems incredibly petty to me but I don't see why I should extend goodwill to her when I get quibbles over 12-78p...