Holy crap Tetra is cute. But why so possessive? I mean, he isn't going out with her, and she doesn't seem to have "marked" him.
I could understand a bit of jealousy, but if she doesn't try going out with him, she should have no claims on him either.
And I prefer harem endings in my harem mangas. I really hope this world allows polygamy...
Oh, and I'm not reading the novel, so please don't spoil me anything.