I started the playthrough today with 17/20, I chose song 2 or 3 when talking to the pianist. Hope this helps.
Edit: Talk to everyone first before seeing Rebecca.
thank you man. I figure out the problem now. When in the mansion looking for the grimoire I chose to take the book over rescue the girl so it automatically made me fail Rebecca path (kinda funny that those two details connected to each other). So I went back and chose the other one and I got through Rebecca now