The way I see it (and I think that's the intention), all the other girls/women in the game are there for MC to get experience. Emily and MC both are rather clueless, but the other ladies are basically there to teach and help MC to be the best he can be for Emily when the time comes, ideally she needs and deserves a guy who knows what he's doing, and not just sexually either, but hopefully also how to treat women, how to talk to them and so forth.
Is it a bit of a missed opportunity that MC has but only one real LI? One could say that, sure. But this is the story dev wants to tell and I personally like the game/story just the way it is.
And hey, to me Emily is cute, she's endearing even with all that Tsundere-like behavior