I do agree with what you are saying.
But about Kuzumi...
Like Kuzumi has repeated many times, he never had any feelings for Tomohisa.
Sure once or twice his heart went *doki doki*, but that is because Tomohisa is just an irresistibly adorable uke.
As for when he wanted to take advantage of Tomohisa, I don't think he really meant to go all the way.
He was doing it to tell Tomohisa to stop talking like he could find a new lover. He was showing Tomohisa that not any man would do except for Hideo. And it kind of snapped Tomohisa out of his giving up mode.
Of course, this is all just my opinion. And it is what I gathered from the story.
No offense! (⌒▽⌒)
I think I get your point (๑•ㅂ•)و✧ thx for sharing your opinion with me
*Spoiler*
About the maincouple:
I hated Hideo-san for breaking up with Tomohisa TWICE. I mean once is okay but TWICE. Tomohisa cried and suffered so much. OMG. Chapter 8.1 made me forget my hate because I started to pity Hideo-san. I mean he had to watch Tomohisa die and lives now all alone... That killed me tbh. That was SO SAD. THE FEELS. I couldn't stop crying.
About the other doctor, kuzumi:
For a few seconds I wanted him to end up with Tomohisa but then he told Hideo-san to give Tomohisa up and I was like "pls Kuzumi mind ur own DAMN BUSINESS!!!" :D Then he also wanted to take advantage of Tomohisa when he was drunk and then I realized that Kuzumi was just a sidecharacter after all. Now I don't hate him but I don't really like him either.