Hate is a big word. Either way, don't waste your time thinking why someone dislikes you. There's always gonna be someone out there who is jealous of you/ what you have and act against you. Be the bigger person (:
If they are ignoring you, being mean to you, or just being plain rude and making fun of you. But people dont always show their hateness because they want to be kind to others even though they hate that person. Or they can be making fun of you because they think its fun but dont hate you.
If they decide to not talk to you or if they say really hurtful words. I've experienced both of those from two different people and they're not fun but you have to get over it. If someone is talking behind your back or they say they don't like you, then you have to move on. I have friends who have never met either one of those people but who tells me to forget about them. All you can do is find others, because the other person is not worth it.
when they try to make your life impossible" wen they tell you mean things infront of everybody so they can embarass you! and they also be talkin about you in your back! and they try to get your friends mad at you" hope i helped" :)