
This is more than a romance or porn or crime story. It is a well written, well drawn piece of art made for folks who enjoy three dimensional characters and a complex plot outside of the romance of the main leads. Yoneda Kou obviously did the research and put a lot of thought into this work.
Did you see all the crap Yoshiro had to go thru to break free of the yakuza? He thought death was his only way out via Hirata but Doumeki saved him from that fate and nearly died for him. Now 4 years later...how is Yoshiro doing as a free citizen? In the past Doumeki was naive and innocent. How did Doumeki find a way to stay in that world? Is the current Doumeki strong enough for the both of them to get together? These are the questions being explored in these last few chapters you call 'boring'. There are plenty of manga and webtoons on this site that can be enjoyed without a lot of deep thinking if this one is not for you. Imho it is worth it to hang in there on this one.

So I'm going to be upfront I'm not reading all of what you wrote. But my opinion is my opinion they are a boring couple. And the main couple who were actually interesting didn't get enough showtime. The author could do all the research in the world it doesn't mean that everyone will find every story intriguing. I didn't and don't.
I still only read this for the orinigal couple even though it's rare to see them. I still don't understand why these two have gotten so many chapters. And the OG couple was like what one volume (I maybe mistaken). Also I think this coupling boring