I won't go onto the ins and outs of each example but I realised a while back that I was being a bit of a pushover. Lots of unreturned favours, one way friendships, that kind of thing.
A good friend advised me that I couldn't change other people's behaviour, only alter my own and the way I deal with things. I stopped with the favours and started politely saying no to people, suddenly I'm seeing attitudes and nastiness that wasn't there before.
Is this a thing? Are some people genuinely only nice of they're getting something from you?