Highly recommend Mai no Mushigurashi it’s about farming and insects but has its own plot line that isn’t just about farming, some ecchi here and there though nothing over the top.
Why add anything to any story? Why have the main character be a girl instead of a guy? Simply because you can and because it’ll appeal more to a specific audience over a general audience.
It’s more like Elma still loves Tohru and Tohru still cares about her but Tohru is in love with Kobayashi. It’s implied that since Kobayashi‘s a human her life span will be short so Elma’s fine with waiting.
To be honest so long as there’s a payoff I’m fine with it. Now if ends in a big fat nothing then that’s a different story. However considering this is a yuri manga there’s probably going to be a payoff.