I tend to have problems when things go from father-daughter to romantic relationships because of how disgusting grooming is. Hell, I've dropped many manga because I could see it coming. Since the beginning, however, this manga hasn't really treated their relationship like a father-daughter relationship. Even the other exorcist recognizes it isn't like a father-daughter relationship. There's nothing wrong with wanting it to be father-daughter, but I worry people are going to be upset if it ever becomes more explicitly romantic. I do think the MC needs to overcome her negative self-regard before they ever go that route, though. Starting a relationship with such thoughts sounds really unhealthy.