I dislike harems and find them intensely unrealistic.
Unrealistic is defined as "Not compliant with reality" but harems are historical fact and even today polyfidelities exist. Reverse harems are still standard practice in some nations as well as normal harems in others.
Author's response
Eh, sorry I should've clarified. I dislike harems as wish fulfilment, where somehow miraculously all women end up sex-crazed and happy. Real harems, such as the ones in ancient cultures like China, tend to be filled with nasty things such as backstabbing, political intrigue, affairs with eunuchs and the murder of infants birthed by other women with the same man, gambits for power, and other such things. I could conceivably enjoy a harem fic with these 'realistic' elements for the plot alone, but wish fulfilment harems are kinda nonsense.
That's my opinion, of course. You're free to like whatever you want, since it is ultimately fiction.
*dynastic China not modern China