Honestly... I'm happy with this ending lol, I liked this series as it treated the content a little seriously, not turning it into humorous hornybait(I like hornybait but I also like the serious stuff). What do you do if your sister is acting suicidal like that, obviously he shouldn't have fallen...
Technically I do feel slight(extremely slight) sympathy for him, constantly told this is for you then to have it taken away right before you can claim can break a person lol but he's still responsible for his own actions green ghost should abandon him already as he's not a bad guy
I mean I'm still seeing it as him desperately trying to keep his sister alive, I don't think he actually liked it and he sees this as the only way to keep her going, however he is normal mentality and can't actually process incest as acceptable