It didnt start with a anti problematic safe first chapters, especially the consent in the beginning which might of rub people the wrong way thus a continued criticism (unforgiving)( you cant convince a toddler to eat their veggies willingly after their initial bad first impression). The other reason would be the shift in what is tolerable/ western community's are a lot more sensitive and full aware of the scenario as they take content more seriously than the content thus these days being labeled to some as problematic if fall in grey zone, its all black and white. People cant take complex stories and flaws these days.
But yeah, its pretty decent story with flaws but the longer the story continues, it starts to get more fleshed out, especially with them being in a established relationship after the initial get together first chapters.
Come on I'd say it's a pretty decent manga
Idk why so many people are hating over it