If someone doesn’t like me, it means they dislike me. No, it just means they don’t like you: whether they dislike you is a separate question.
If something went wrong or someone was feeling bad, it must be my fault. No, you’re not the center of everyone’s lives: other things are at play.
If people don’t invite you, it doesn’t mean you’re banned–ask to go if you want to and it’s appropriate. (See 4 Kinds of Invitations)
If someone dislikes, it means I’m unliked as a person. No, it means that one person dislikes you, and it doesn’t make your entire existence unlikeable. Is liking a fruit an objective truth? People are different, some like apples, others like oranges: liking people works the same way, some will like you, some will not, and that’s OK. (Watch the movie Wreck-It Ralph)
If I’m not perfect, I’m horribly imperfect. No, there’s a range: you could make mistakes once a minute or once a day. Don’t let one mistake feel like many mistakes, and don’t let mistakes in general make you feel imperfect: everyone is imperfect, not a big deal.
More advice: Common Relationship Mistakes