I'm not into Yuri and I'm avoiding it, but I have read this since day one when the manga is only labeled as Slice of Life and never expected that Kei would bring this manga downhill to the ground and to think that the Shoujo Ai tag is only there solely because of Kei, I actually liked Kei at the 2nd chapter because She's a tomboy and the male lead's Osananajimi, I thought She has a thing for the male MC but I was proven wrong.
I agree with KazumaLee94's comments, people who are angry towards us people that only pointed out the flaw of this manga should understands more that this manga is just bad in every storytelling aspect and Kei just made it 100% worse (Except if you are some Yuri junkies fanservice chaser, you still can survive this though.)
And yup, Kei is the sole reason this manga is going downhill, without her, this manga would be still doing okay I believe, what a waste of good art.