I've been reading/watching harems for my whole weeb life, and yeah, I think it is really sad.
You've got some guy or girl who's spent most of their life being average when suddenly, there's several people who see them as something amazing and important in the world. The next thing they know, these people are attracted to them, but MC is either too insecure to believe they're all in love, or too dense to even imagine it.
That's kinda why personally, I'm twisting and messing up the genre as I write it. I think it's... sad when someone's got all these guys/'girls' hearts in the palm of their hand. I started my story before the (would-be) female lead transferred to the school because, I dunno, I feel like there's more to life than love sometimes. Sure, it's great and all, but it's so WEIRD when the dudes are just her... love-slaves.
I'm weird too. I always wonder more about the people in the harem. Was the problem in their life really so bad that just meeting this girl solved their trauma? Isn't anyone scared of all these brainwashed guys?