What could cause someone to dislike you when you haven't done anything to them?

Jealousy , rumours , other people’s negative opinions , fear , your success , thinking your happier or have a better life than them , insecurities, getting bad vibes or the wrong vibes , judging you by the way you look or by the first impression of you. I became Freinds with a girl who bullied me and she told me she hated the way she looked and wished she was my size and she too had depression and problems and one I became Freinds with thought I was a creep as I smiled at her then we became Freinds after we started talking.

Not everyone is going to like you... Doesn't matter how attractive or nice you are... That's just life.. Don't let it worry you

Insecurity. Sometimes it’s about them.

jealousy is quite common

Maybe you remind them of someone they don't like, or your personality is totally the opposite of yours. Or feel jealous

Maybe somebody talked some shit about you to them.

Who knows