A question for all the social dynamics experts. I've come to notice a pattern in my life which seems to go something like this:

1) I meet someone and decide to be nice/kind to them, as this is my default nature (I try to be kind and respectful to people until they give me a reason to do otherwise). We develop a friendly, although not very close, relationship. Sometimes there might be a power imbalance where I would be at least somewhat higher social status. E.g., the other person is the maintenance guy at my apartment complex, or a lonely older neighbor woman.

2) This other person wants and expects me to do something with/for them. However, I'm not under any obligation to do this thing. I disappoint them by not doing the thing.

3) They lash out by doing something "bitchy" (usually passive-aggressive).

I understand being disappointed, but their response is out of line and not something I deserved (at least I don't think so). Am I just noticing this when I happen to be dealing with bitchy types and it's nothing to do with me? There are always such people, but my subjective opinion is that it happens more than it should. I almost think they see me as weak or a pushover so they can get away with this shit. Do I need to project strength more, maybe I'm too nice?