I figured this was because this game is still updating
Rather pointless to have an ice queen waifu type that dosen't melt. Especially with the various lovey dovey moments she enjoys.
Nothing states she's not looking for a partner or that she isn't open to one. And you still appear before her and early on her diary states she really likes you.
(+ all the flustered moments and the entire wild lose scene where she's literally claiming you)
Not to mention the love bar she meant to give to someone special and she lets you have it.
There's also the dream sequence. Her diary and customer book wanting you as a pet. And extra(yet also seemingly unfinished) dialogue when you wear a collar near her.
Overall, her current content equals in length to Kotone's. Except Kotone actually progresses beyond her initial sadistic attitude(Same with the Manticore that actively denies wanting a relationship but that gets solved nicely)
(Also, if you spar with Venefica when she holds back. She has a debuff called "Venefica's love")