I don't think this song is about a girlfriend or a girl in general. I think it's a personification of a girl's addiction. "Her friend's a bitch and needs to go" is referring to ciggarettes in the first part and alcohol in the second part. Even the verses saying "I'm in the house" he is saying nothing will get her to stop, not a new boyfriend, not a kid and definitely not a piece of paper. He hates that she is unwilling to stop these vices because they are killing her and making her look careless and he tries to help her but she never appreciates him or accepts his help.
I don't think this song is about a girlfriend or a girl in general. I think it's a personification of a girl's addiction. "Her friend's a bitch and needs to go" is referring to ciggarettes in the first part and alcohol in the second part. Even the verses saying "I'm in the house" he is saying nothing will get her to stop, not a new boyfriend, not a kid and definitely not a piece of paper. He hates that she is unwilling to stop these vices because they are killing her and making her look careless and he tries to help her but she never appreciates him or accepts his help.