Single women - Diverse Tastes - Desperation, joy, adaptive

Single Women: In a world where women are the ones who desire to be in harems and men are apathetic to the idea, you are unique. Why? Dunno, perhaps you were isekai'd somehow? Maybe you grew up extremely sheltered? Either way, the single women shall easily be claimed by you. Why?

Diverse Tastes: In this world, men have such specific and detailed requirements for whom they court, finding one who's attracted to you is akin to finding a shiny pokémon. Their requirements could be something as insanely specific as "Redhead with exactly 123-146 freckles, white skin, weighing 56kg and being 170cm tall, who must like country music and abhor rap, etc." Identical twins and triplets are considered lucky, as the odds of them landing the same boyfriend is higher on average.

You, however, in comparison, have extremely diverse tastes. Even if by our own world's standards your tastes would be considered high, in this world your tastes are easily met, as they are way easier than the standard troubles you have to go to in order to court a man.

Desperation, Joy, Adaptive: Finding a man attracted to them is rare enough. Finding one with as diverse tastes as you is practically a world-wonder! The fact that you're likely to say yes to them inviting their own friends to your harem, no matter how different they are, is a chance they can't pass up. They'll be desperate to join your harem, joyful to have found someone attracted to them, and adaptive to whatever requirements you have, as they are trivial in comparison to the requirements they would normally have to meet.