You totally read my mind everything you said is true but why I feel the anime is terrible is because Nao was the cause of haru's misfortune and from all the realities Haru was contented with only his sister. When Nao made Haru do her when they where young I think it affected his mind and psychology and I'm sure that moment was all he could think of. I have a friend in the same situation but he was cured because he came out with it and told his friends, now he is living a peace life without any insest acts. If you've washed "FLOWERS IN THE ATTIC" I think you would understand that because Sora was not social so she became reliant, most girls except very strong women, no even most people always need a shoulder to rest on. I believe they don't actually love each other but as I said Sora's reliance and what she saw Nao doing Haru when they were young, made her feel she had this love for her brother because she felt jealous. While Haru couldn't be strong because he felt he needed to protect his sister and transforming simbling love to unruly love. To go straight to the point the anime started boringly then became mildly interesting, then became useless when Haru couldn't realize he was suffering from trauma and that Sora didn't realize she was just reliant on her brother, making it a very painful thought bordering and sad anime.