I think it is funny people talk about the harem not being realistic but I bet that the same people would rage if I said that the only way it would be realistic in today's society is if it was actually a polyamorous or open relationship where all parts had the same rights and by that, I mean that the girls get to fuck whoever they want as long as the MC does.(this was written in a joking manner)
That apart, the Mc is abrasive but not abusive, at least on my run, I will say that I don't know what the woman in this game sees in him he is not my type by any stretch of the imagination and his personality is not good either, I'm not sure he would even pass my decency test but that we will figure out next update or at least how close he would be to pass or fail(probably gonna be player's choice though), but he isn't too much of an asshole either, yes he sucks at properly expressing his emotions but that is getting better, which I guess is his whole character arch you know getting better, but yeah this is my 3 cents, it isn't unfeasible but it could do with better reasons why the characters are into him, although again people are just attracted to who they are attracted to some times so I don't know anything is valid I guess.
Now for some validation of the harem, his sister has been in love with him forever so that ain't changing soon which means she is for sure a +1
.Milly has Idolized him forever and if I'm being sincere her case should have some therapy involved before they ever got together (but that is true for every character so far) since it could be besides an obviously genetic thing a trauma response.
His mom well genetics since it seems incest runs in that family and she might just feel like this could mend their relationship, basically everyone in the family is fair game because they have pre-established relationships.
Jules, I don't get it, maybe it is because of her connection to the Mc's ex, she is looking for her lost lover/friend on him, also some idealization because she heard a lot about him before.
The blond that I forgot the name, she had a crush on him and he basically saved her life and at least on my path their thing is mostly him helping her explore her sexuality from now on but at the same time him failing on exploring his.
For the rest is basically the "every character wants to jump on the MC's dick for no reason" trope, All of Milly's friends seem to almost instantly be into him at least sexually.
So yeah blame the trope it isn't the most believable, I could probably come up with reasons like, Kimiko(?) not having access to many men that she can trust on that level, her sister is curiosity, the super hot short girl is curiosity as well and lack of access to someone better, the other friend is curiosity, and so on, mostly I would throw the blame on the "younger people being into older ones" thing, I sure as hell am into both older woman and some older man so I get that.