Just found this. I was wondering why there was an option to 'spend time' with all the shopkeepers, but no way to actually to get them to agree. (I dunno if this is intentional, but Shikia always telling you she's tired and you can hang out later, even in the morning, is really funny, because you eventually realize she's just being polite about not being interested.)
I actually really like this aspect, tbh. It makes it feel more like this is an actual world that doesn't solely revolve around you. Not every girl is going to want you, even if you're 'persistent', which makes it feel more meaningful with the girls who DO like you.
This is also why I like Jimmy and Kiuta. They're other male characters who have important relationships to your love interests, and they AREN'T jealous or toxic romantic rivals. It makes the world feel bigger, because everyone has relationships that are independent of you, and those relationships aren't discarded or replaced by you.
tl;dr the fact that you can't romance everyone/not everyone is interested actually makes it better, imo.
I really like this game. The lewd stuff is great, but I am also, regrettably, legitimately invested in the world, story, and characters. Keep up the good work!