For those thinking that the author isn't focusing on the LGBTQ+ oppression, we're only four chapters in. Besides it looks like Yukari is in the closet about her sexuality, remember her family is wealthy and likely well known and well respected so she has to worry about how her actions would affect the image of her family. I think this will definitely be a plot point later on, especailly after learning that Ayu is gay and figuring out herself as well. Also we're ultimately following Ayu and she is desperately trying to forget the awful way everyone in her hometown treated her. I hope she can move past it in time, but that will probably require trusting Myaa-chan and Yukari enough to come out to them and let them support her as she grows.
As for the sunglasses, she has a blue eye and that makes her more sensative to bright light. My wife and I live in Cali and she has blue eyes, when we go out for walks (especially in summer) she can't go outside without sunglasses or it's super painful for her.