I dunno why people don’t like this. It’s a deep story and an interesting one. I unders...

Why people don't like this series

Invalid reasons:
1. It's popular
2. Women fetishising gay relationships

Valid reasons:
1. The story and characters aren't that deep or well-written. It sounds deep and poetic, but if you actually think about it for 2 minutes nobody actually thinks or acts like an actual human being.
2. The author keeps recycling the same premise/plot, but just introduces new couples that get progressively worse and don't actually add anything to the overall story. This just seems like an attempt to stretch out the series as a cash grab rather than an effort to explore themes or expand on character development.
4.The quality of the couples have gotten incrementally worse since the first one, with the latest (Hiragi/Shizu) being the worst written yet. Shizu barely has any personality, and instead of watching characters fall in love for understandable reasons, we skip any form of development and are just told they've both loved each other for years.
5. The story equates male love/lust with violence and sadism. The uke characters have to endure some form of fear/violence/abuse first for the sake of 'loving their partner". The dubcon scenes are used as a cheap form of edgy shock value, and then quickly brushed aside or forgotten without properly dealing with the consequences. This has the added effect of making the uke's look like pushovers without any sense of self-respect, and the semes look like inconsiderate sadists.

1. Well maybe it isn’t that deep, but when u think about this couple reasons of their story looking like this u will find out that they were and still are young. They just have trust issues and lack confidence.Also believe me there’s a lot of people who act similar, maybe not that incoming sex scene (if it will happen)
2. As for me it’s great that we get to know other couples as we could already spot them in the main couple’s story and it does add some context to the main story tho. And well in real life don’t expect people to develop fast or make some progress in relationships well instead of doing time skips author is trying to show us some others stories connected to the first one.
4. Actually we were given the reason why hiragi loves him and I don’t think it’s necessary to expend it. And as for Shizu personality it exists, believe me or not, but it does. He’s just we’re introverted plus we don’t get to know his point of view yet. Well in your way we can say Sato is also personality-less. But when considering it deeply we can understand him. Well couples may get worse but I guess it also have sth to do with the thing sb can relate or understand better.
5. Ur right with that, but we also get to know painful story of Akihiko so it’s not only for ukes (not to mention Yuki). And in each story there’s the point that the ukes are the people who have completely fallen in love and are able to bare anything for that love. But Akihiko also were like this and then even changed.
Im not saying it’s the best manga ever I was just pointing to this story. We don’t have it completed yet, maybe we’ll understand more soon. But as for me if author have continued with only satouenoyama’s story it would be pointless. Well do we want to get relationship’s problem only?

1. Being young doesn't excuse poor writing and predictable characters. There are plenty of stories with wonderfully written child protagonists.
2.If the additional characters were well-written or developed in an interesting manner then there wouldn't be an issue. But they are not, and by and large they just take up too much space within the story.
4.No we aren't. Hiragi mentions that Shizu looks pretty in ch.32 and that's the most substantial we get. We are never shown why/how the two fall in love, we are just told that they have been since childhood and are then forced to sit through a bunch of misunderstandings for drama, which do not contribute anything to their character development, overall plot or theme of the story. seriously, had their story been omitted entirely we wouldn't have missed much from the main plot.
Also, Sato actually has a character AND development, at the end of volume 2 Mafuyu gets the confidence to love again and move on with his life and this a direct result of his relationship with Uenoyama. He GROWS through the relationship. Both Hiragi and Shizu don't actually change as people, and don't even get me started on Akihiko's terrible redemption arc.
5."the ukes are the people who have completely fallen in love and are able to bare anything for that love"
And therein lies the problem though. When you say "bare anything" it implies that no matter how violent, hateful, mean, and cruel the semes are, the uke will alsways endure it for the sake of "love". It makes the ukes look weak and desperate and like they have no sense of self-worth. This was part of the problem with the second couple in the series. And Sato, for all his introvertedness, is still at least his own person, and not desperately lusting after Uenoyama every waking moment.

"But as for me if author have continued with only satouenoyama’s story it would be pointless."

I don't think this series should have continued at all. Given was originally only meant to be 2 volumes long and that makes sense from a story perspective because at the end of volume 2 Mafuyu gets the confidence to love again and move on with his life. The concert wasn't just meant to be the beginning of Mafuyu's new love, it was supposed to be the climax of the entire series.
But now, as a consequence of stretching this series way past it's planned resolution, the author has had to resort to recycling the same formula over and over again. Instead of moving past his dark past, Mafuyu is still wallowing in it. Not only does this unnecessarily stretch out the series, it also undoes most of his character development.