
I don't like Miura and I can see why your opinion might be unpopular but I appreciate your articulation in trying to understand both their situations.
I know that even I have said "look at Jun's signals" and I still believe it but I think some people forget also that Jun is also the same age as her. She has BL manga to reference but his understanding of romance is pretty much as limited as hers. The only difference between the two is that his understanding of romance sprouts from lived realities. While Miura focuses on the fictional aspects of manga and BL manga, Jun is first hand involved in sexual relations and online communication with others. It may seem like he has more resources but these two teens are both still pretty naive to romance. It is important to comprehend that Miura's idea of romance is filtered through fiction while Jun's is through reality because then that makes the reader understand Miura's privileges. Just like manga, if she doesn't understand why Jun put her in this situation, she can easily put it beside her and forget about - as if his life was a fictional part of her life. But Jun is living his romantic experiences. He is not belittling Miura. He likes her but he is also trying to understand why he doesn't LIKE her. Miura is not a villain but her privilege allows her to use her ignorance and naivety and GET ANGRY while Jun's ignorance and naivety about romance is criticized by Miura who was two-timed. Her privilege as someone who can shut off gay experiences as "fantastical" while Jun has to learn that gay experiences AND straight experiences are all real is what makes me dislike Miura. This is privilege; when you don't have to worry about "other" people. But Jun has to always keep the whole world on his mind. Yes, she is not an evil person but ignorant words are far more dangerous than fully physical harm.
I love how non-combative you are about your opinion. I hope I sounded non-combative too - I am not trying to start a fight. Your opinion has helped me in prying my eyes towards Miura lol.

No thank you for sharing your opinion as well! I understand where you are coming from and can understand why her privilege to shut off that part of the world would be infuriating to some. I really hope she grows and maybe from Jun opens up to reality more to learn to see the side she’s blind to currently. I also really hope Jun learns from her the more optimistic side of love and friendship where he can learn to not define the barriers of his friendships by the fact that he’s gay and learn to accept himself more.
I do believe she is very ignorant and if she doesn’t fix that soon, it’s going to be and already is honestly harming her and everyone around her but I don’t believe she deserve the hate she gets.
Everyone seems to be demanding that she “look at the signals jun is sending out,” but forget she is literally a 15-16 year old girl in her first? relationship who’s only reference to romance is probably manga and her senpai and friends who glorify their own relationships to brag. Jun has been sending out very mixed signals to her as well, first with accepting her confession then kissing her back and progressing until he suddenly backed off but even then he still said they were going on the double date to the onsen. Dating is not the end all be all where once you date, you’ll know everything about the person like in the shoujo mangas, dating is another form of getting to know someone in the context of starting a partnership. It would be great if she picked up the real signals but if Juns trying to hide it then why is everyone getting mad at her for not seeing something he doesn’t want her to see when they barely know each other.
“I don’t believe they exist around me.” Was the height of ignorance but there was an obvious solution to curing it which was have him opening up to her and revealing that he’s actually gay in the first place. Yes it would have been hard to do considering all the emotional trauma that could happening. But she isn’t a bad person at heart and after a little eye opening conversation I believe she would have changed for the better if it was early on. But now that they’re dating, what is she going to think? My boyfriend is actually gay so why did he date me? He’s seeing an older guy? So am I just a shield for him? That would leave a 100%. worse image on an impressionable teen who’s probably not used to thinking with her head.
Honestly I believe both of them are victims to their society’s social standing on the issue. Miura has ignorance the level of the clouds which makes her look at gay people like fairies which is harming Jun and Jun is so afraid of being outed and subsequently ridiculed by society that he is harming Miura and himself in the process of trying to appear “normal.”