I think, what the interpretation could also be, next to someone new to love or even a person that has broken someone's heart, could be an insecure person. Cause at the beginning, she is singing about her self in the worst way possible. She is a crook, a bad person, but she knows. In the meantime, there is the partner, who actually doesn't think that way at all. They love the insecure one so much and do anything for them, but the insecure one is so afraid to hurt the other person, to not be good enough or after all enough for them. So she builds a wall, and says she can't love, just so the other finally leaves them alone, but they won't. They won't cause they hope, if they keep it up, maybe the other sees that everything will be okay. A bit like Anna and Elsa, but as a romantic relationship between non relatives of course