You are reading shoujo harem manga and you come across a surly, sarcastic boy who seems perpetually annoyed with the heroine yet takes care of her? He's also dark-haired or just dark looking in the brooding sense (Tomoe from Kamisama Kiss is a silver kitsune and yet he fits the type through and through)? The only emotion he shows to others is anger/annoyance? Has no friends or at least behaves like he doesn't?
That's him. That's the one. He will be her favorite harem member and her ultimate choice.

I think Ouran is one of the few exceptions.

But why?
It's not just the bad boy type. There are many types of bad boys: a hot-blooded challenger (usually he'll be one of the rivals), a mysterious bishounen (mostly likely the real villain of the story or a converted councillor. But they very rarely take center stage.

Err, isn't it because people like tsunderes the most (relevant to both genders)? And mix the guy into a "bad-boy" and girls swoon all over him. I guess because he's like a challenge (ie harder to get)? It is also noticeable how the female protagonist is a naive idiot, so it's like an opposites attract thing: gruffy ikemen, tsundere guy (most likely smart) x plain, dumb heroine. I personally don't like those kind of guys, especially in real life. I personally prefer, fictional or not, a "boring", nice, imperfect guy- as long as he tries hard for you, it's aww~ To bad that never happens in fiction and in some cases, in reality too.

I'm in idol hell T.T

Harem is the problem here. You will hardly find any attempt at characters' depth in a harem manga. They're here only to fit their type. And as LettuceGarden said, the tsundere type is the most popular, hence your winner in both shounen and shoujo manga. Take the harem genre away, and you may find some more interesting themes.

My war against harem keeps on going 🤣

My current top 3:
Fullmetal Alchemist
Pandora Hearts
3-gatsu no Lion

My rule is that the protagonist will pretty much always end up with whoever they encountered first in the manga. So if they have a childhood friend that appears later it doesn't count. It works like 9/10 times. Usually it's pretty obvious who the MC will end up with and the other harem members are just there for "flavor"...whatever that means. I really don't understand the appeal of harems in general, male or female.

Cynicism at its best.

I agree with conquerorofheaven. I guess that people like bad boys and the tension they get when they appear in a manga. Also it makes things more unpredictable and when the male lead expresses his love, it really emphasises that it's true love cos naturally he'd be cold towards a girl

"No single raindrop thinks it is responsible for the flood." Implying that every time you repeat a habit, it's another .001 figure added to your risk of suffering finite oblivion.

It's because of the short straight black haired man and the long // // // woman < What are those? 🤨

Yeah, eexp, that's usually the way to figure out love triangles where the two male leads appear simultaneously. I like to call those two-person harems, because the plot is developed the same shitty way. Contrasting hair is supposed to be more visually appealing is what I heard. Nice pic, by the way.

I don't like harem manga too.
You know it's always that same guy in the end who gets pick out by the girl.