I see people keep saying this but there have been no valid data to this claim. Like this is more of a easy story ( a simple love triangle and work office/gym love) so most reader are people who seek for fluff (and some spicy scene) so when confronted with as you said morally questionable mc it more likely to trigger them as they been used to fluff story with a protagonist halo MC
But when it comes to rapey story the target audience is of course different and in most cases only small portion of the fluff reader actually go and read the rapey story. Majority of rapey story I encountered have a story building that focus on the ML bad personality since the beginning chapters and that chapters is what filtered out people who enjoy THAT kind of story and people who against it. People who stay of course would less likely curse the rapist ML as they went in knowing the type of story and stay because they enjoy it or at least intrigued to keep track of the plot.
So yeah by looking at it briefly rapist ML have smaller hate . Anyways hope it understandable.
It does make sense that the audience is different, hence the reactions as well.
However, I respect the author to do her thing, not bowing down to the typical yaoi tropes (second ML almost never sleeps with MC, seme is mostly the promiscuous/experienced one etc.).
And Param's choices are not that far away from reality, I'd personally wouldn't do it, but I can understand Param.
I'm not defending Param here, poor Hwi(〜￣△￣)〜
But to be precise, they weren't in a relationship yet. It's astonishing how much people would hate on a character that might be doing something morally questionable and gets WAY more hate than a typical yaoi character/male lead that raped the MC and then has lovey-dovey relationship with him.