A lot of people might think that this is just a sad song with Billie trying to convey the message that she's 'depressed'. But the meaning of this song is a lot deeper than just that. This song is basically addressing a relationship that is toxic in a way. This is song basically a way of saying "just leave me alone i'll call you later". Billie is addressing how much this relationship is hurting her. They are not suitable for each other at all, but she still tries to make the relationship work because she still has feelings of affection and love for the person.