Eh, maybe? Personally, I wouldn’t consider a love triangle enough to be a harem, and I don’t see that any of the remaining girls see themselves as a love interest, just platonic. “Harem” as a genre is rather vaguely defined, though, so I won’t blame anyone for seeing it as one.
It might be overplayed, but Re:Zero does fit that bill. There is a romance, but only one, and it doesn’t play off the ecchi comedy tropes. It still is based around an oblivious boy, but it’s used as one of his major character flaws, and he has actual character growth.
It had a huge following when it was airing (still kinda does) to the point where it got annoying, but don’t let that color your perspective of the show.
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