Mangago sometimes messes genre tags up, though this does have a yaoi tag (though it's not) and technically most bl is shoujo since it's targeted towards girls and younger women. They're usually published in specially bl magazines though, but this one has more characteristics of your typical het shoujo manga.
That being said in Japan they just use "bl" as an umbrella term instead of anything like shounen ai/yaoi.
i see, though it would be nice if we could more clearly categorize certain stories as there are so many out there that it's hard at times to find what you're really looking for. in my mind i associate shoujo with a female mc, shounen ai with a more gentle and lovely bl without much sexual stuff happening, and yaoi as more adult bl that is pretty common everywhere you look, i feel like esp in korean manhwas that can get pretty extreme. in that sense I'm a big fan of shounen ai and shoujo and would love it if it was easier to find the type of stories I'm looking for. just ranting tho.
why tf is this in the shoujo category? and it doesn't even have a shounen ai tag, what's going on??