I think this is a song about relationships. She has fallen for girls and boys, but she is reflecting on how toxic the relationships were. Even when she is talking about the other person she is also talking about herself. Through love we learn about ourselves, the parts we like and dislike. By the end she learns to keep her distance and the "her" in the last stanza is herself. She can't help herself and she will stay untogether.
I think this is a song about relationships. She has fallen for girls and boys, but she is reflecting on how toxic the relationships were. Even when she is talking about the other person she is also talking about herself. Through love we learn about ourselves, the parts we like and dislike. By the end she learns to keep her distance and the "her" in the last stanza is herself. She can't help herself and she will stay untogether.