This might just be me when it comes to Kuroshitsuji/Black Butler as a whole
But it really, really confuses me whenever I see someone say that Black Butler is marketed towards women. (Some even go as far as to straight up call it "shoujo")
Like, I'm not saying women can't or should not be allowed to read this manga, (cause that's bullshit obviously, speaking as a female myself)
But like 80% of the time Black Butler is actually classified as a "Shounen" manga. (In case you aren't familiar with Japanese terms, "Shounen" basically means "manga targeted towards a male audience of about 12-18 years of age." Its female equivalent is "Shoujo")
Again, this is most likely just me, but I can honestly stand a bit more behind the shounen term than the shoujo term in regards to which category Kuroshitsuji belongs in. Sure, there's clearly a lot of (mostly squicky) fanservice with the protagonist, but there's also a lot of fanservicey shots regarding its female characters (examples being Beast, Ran-Mao, etc.) which is, y'know, typical shounen stuff.
But also more importantly the magazine the manga was originally serialized in (known as MonthlyGFantasy) is a Shounen manga magazine.
So if Black Butler is classified as a shounen manga, how would one explain its very obviously shoujo qualities?
My personal theory is that it's a way of branching out and getting more people to read this manga.
Here's an example; remember how big My Little Pony: Friendship is Magic was back in the day? Long story short, it was a show that was originally targeted towards a very young female audience, but thanks to its storytelling and characters, it grew a fanbase that was very far beyond that target demographic (an entire fandom mostly consisting of young adult men who liked cute and colorful ponies). As the show continued airing, it even started pandering to that fanbase.
TV Tropes calls this "Periphery Demographic": "Fans of a work that are outside its primary target demographic. Perhaps much more than within."
To me, it looks like a very similar thing is happening (or rather, has been happening) with Black Butler here. Originally had a shounen audience in mind, gained a strong female fanbase for its... certain qualities.
Of course, this is all coming from someone who is not Japanese and knows very little about manga demographics and stuff. So if I'm wrong about anything I've said (which I most likely am), please do correct me.