Things don't exist in a vacuum. You should be aware of that much at least. People are complaining about the slut shaming to show those who it may apply to that not everyone will look at them as evil, no matter their reasoning, and to suggest the values are being misplaced or even unevenly applied. You can say Saku shouldn't be a whore, but it isn't like the MC is clean. He's really pushy. If Saku didn't have genuine feelings for him, it would be harassment. And a lot off the comments are suggesting he owes it to MC to be open and stay pure, etc. Some are acting like MC already owns Saku.
Yes, this is a story, but sometimes the story of a story is more important than the relationship and sometimes things build up to a healthier place if given time. You can read a story for an interest in a concept or a character. I've done that plenty of times.

i'll never understand why some ppl complain so much abt "slut-shaming" in the comments of these types of yaoi. and then rant about how real life ppl can sleep with whoever they want. like, duh? but we're not talking about real life, we're talking about a work of fiction where the reader is supposed to be emotionally invested in one couple.... like if you're emotionally invested in a (FICTIONAL) couple it's not that weird to say seeing one or both of them sleeping with other ppl (no matter the circumstances) might make you feel cucked yourself and therefore need to vent on here lmao
as long as the ppl shittalking the uke OR seme for sleeping with other ppl aren't taking that same energy into the real world with ppl who mean nothing to them,,, WHO CARES? its a STORY, these are NOT REAL PEOPLE. they are not going to get their feelings hurt because some 18 year old mad at a yaoi theyre reading at 3am said some choice words lmfao. go outside, touch some grass. i promise you a good majority of the ppl youre bitching about could not care less about who people in real life sleep with as long as its not their own partner and theyre not cheating on them fgshgdjhsg