I think I'm a brat
Why do you think you are a brat?
I think I'm a brat because I always yell at my girlfriend and stay out late at night
I understand that you like to stay out late at night, but you need to take in consideration of the feelings of your girlfriend. You should not yell at her and act like a spoiled brat and only do what you want to do.
I can't help myself, everyone likes me and I am so popular. I feel I can do whatever I want.
It isn't very fair to disrespect your girlfriend. If you keep treating her poorly you might end up single and alone.