This tierlist showing both affection and romance progression is very confusing. Croixelle route, for example, has much more romance than Makla or Kive routes, despite her being more cold with MC (can't really say that Kive or Makla are much "warmer" towards him, Croixelle is just trying to hide her feelings).
Naya loves MC as one would love a perfectly cooked steak, not as a partner.
There is no way that somehow Yakuu treats MC worse / has less romance development than Kendra. For the most part of her route, all that Kendra did was reflecting on her relationship with Maryen, it looks like she's not really into MC at all. Only in the middle of the route she appreciates MC for the first time (I'm talking about Vai'Klis house, when they were casting away ghosts), the rest of it is basically treating him as her posession.
Nyxmay is unfairly low because her "romance" side collides badly with her "treatment" side. She opens her most sacred memories to MC every night, but at the same time keeps beating most lethal bodily harm world record every afternoon, so it's confusing.
Pyeka is... hard to tell, but definitely more than B. Yes, she sees MC more as a very lovely thing to have, but that's the closest you can get from a Homaspernia giantess in owner-slave relationship. MC is more like a super VIP slave to her, yet she appreciates his kind heart at least.
Not sure if Diula belongs in A, she's a bit slow after all, so it's hard to determine what exactly does she feel towards MC. Same goes for Sheina, but because it's her thing to be teasing and all, so it's also hard to say if she "loves" MC or just having a good time with him.
By the way, Geminigems didn't make it to the tierlist. I bet they would go in B tier, because they are not that much into MC as a partner, just very kinky about his size. Also Helga, but she would probably go into "Don't know yet".