I hope other girls will change your mind. But congrats! You already chose your favorite! For now..
After finishing this version, I have to say that, first, even though I don't know anything about Yue, apparently she's already in some kind of relationship with the MC, so my intention is that she doesn't break up with the MC.
Of the other LIs, I really liked Lily and I also liked the MC's mother (I don't remember her name being mentioned at any time) and Keiko. I guess Chloe isn't part of the LIs.
I don't consider Cecil to be a LI, although apparently she is.
If I have to choose a favorite she would be Lily.
I personally don't see how a non-harem game would fit my tastes in this case: I haven't intention of the MC ending his relationship with Yue. And I'm also interested in the MC starting a romantic relationship with Lily (if she's not a LI, then I'm directly not interested in the game at all), and if possible also with Keiko and the MC's mother.
In fact, my interest in Lily, if there isn't harem, is incompatible with maintaining the MC's relationship with Yue, and really, after playing this version, either the MC can have a relationship with both at the same time or I prefer not to play ( and if more LIs can be included, the better).