These people who don't like manga with "used goods" just feel pity for the girl.
They, those people, hate the manga because of the circumstances it delegated to the girl. They feel anger, pain, sadness, disappointment, and a myriad of other emotions in place of the girl. They just regret not being there for the girl, not being able to do something, this results in them hating the situation.
I understand them, because what I wrote was what I feel. I want to punch, and strangle and maybe even kill the people that hurt this girl, but knowing I won't be able to do so made me more enraged. Even if these characters are just fictional, being able to see what happened to them angers me, us.
These conflicting emotions lead me into dropping the manga. I feel so powerless, I just couldn't bear it. I would gladly accept criticism since it might open my mind, change my views and maybe even change me into a better person overall.
I know it might sound childish (since I am childish), but I'm being honest here and I believe this is also what some others feel. I just wanted to say my part, I hope you understand and sympathize with me.
Edit: I just read chapter 7, during the first part, I felt fire burning in my heart. After reading a little more, the fire went away. I did this to confirm my feelings, I am angry at those who took advantage of the girl's situation. I dislike it. I want to have been there with her to offer my support, but I couldn't have.
However, I do agree that she was lucky. If the author made it more filled with despair, I might have rated it a 7. Acknowledging the girl, and her feelings and the "plot" of the story, I gave it an 8.