I'm going to have a fight with my girlfriend because she prefers a friend over me
Why do you think that she prefers this friend?
Because she just wants to go out and have fun and drink and  not be bothered with me.
I am sorry your partner is choosing a friend over you. It is reasonable in a relationship to expect your partner to put you first. If your girlfriend continues to refuse to put you first, you should consider breaking up.
What, are you a moron? Are you a stupid bitch?
No I am just trying to help you with your emotions. I get why you are upset that she prefers her friends over you.