It felt that way for me because Frost seems to whip out her sword or threaten Claire's life at the drop of a hat, even if she doesn't mean to actually kill her. I probably wouldn't feel this way if it took at least a bit longer for Claire to feel something for her, tbh.
I won't lie, I don't think I like this one very much. The relationship between Clarice and Frost feels at least a little abusive? In a "the author doesn't realise it" kind of way. It reminds me of beauty and the beast, if the beauty fell for the beast first and set out to fix him.
I really like this manga but like, my biggest worry is that it'll end up actually being a game for Fuwa or something, and that she'll hold no romantic feelings for Marika. She did this almost on a whim in the first place, right?