Look, my idea for a harem anime would be one where the protagonist has been dealing with all of them for quite some time and has been confessed to by everyone, and it starts out with him basically saying "FUCK IT, if you all want me, you'll have to share me!"
The conditions being, you can drop out at anytime, but everyone has to share him equally between each other, whilst trying to win him over to some extent.
Hijinks ensue.
But honestly, if a lot of women/men all fall for one individual, and that individual loves them all back, all things being equal, at least attempt a compromise. If it doesn't work, it doesn't work.
Hell, the harem genre has fucking existed since the Tale of Genji, and even in that he gets all the women in the end, even if he marries his aunt. (Don't question it.)
@BalrogDeMorgoth