See the senpai comment is my issue with the series. One of my favorite characters is Haru from Beaststars, so it's not coming from an incel perspective like quite a few have. My issue is that their characters stop making sense for the sake of.... well, for no fucking sake.
First she's outspoken but inexperienced, then it turns out she's already promiscuous. She's all about "master", but then was doing it on the reg with "senpai" at the same time. She was annoyed and impatient that he wouldn't date her, then it's like they already forgot they technically are. She rejected senpai and said she's exclusively MC, yet now here she's talking about doing it with him again.
Her character is whatever the author feels like that chapter. In that same way, is the MC a cuck or not? Again, depends on the chapter.