This song isn't about having someone who's there for you no matter what it's about the total opposite. It's about being lonely. She's let her problems and her misery isolate herself from everyone and she doesn't feel like there is anyone who cares about her happiness or what she's going through. The "but you" is referring to herself, I thought that was obvious. IMO the problem she is going through is related to drug addiction: "light up another, I can taste the filth inside, I need to cleanse myself".
This song isn't about having someone who's there for you no matter what it's about the total opposite. It's about being lonely. She's let her problems and her misery isolate herself from everyone and she doesn't feel like there is anyone who cares about her happiness or what she's going through. The "but you" is referring to herself, I thought that was obvious. IMO the problem she is going through is related to drug addiction: "light up another, I can taste the filth inside, I need to cleanse myself".