You can recommend me even anime, doesn’t matter what country or language. I’m hungover “Moon River” and can’t seem to find other good reverse harems. I’ve watched and my favourite : “Go Ho’s Starry Night”. And loved these : “Shining Inheritance”, “Princess hours”, “The Heirs”, “Unique Lady” and lastly “Cinderella and 4 knights”. For historical romances, my favourites  : “ Go princess go”, “My bratty princess”, “Princess Huai Yu”. I love a very strong rivalry between the male leads. And preferably more than 3 guys after her, love watching a few guys literally fight over a girl. And I’ve also watched all the “Meteor Garden”, including the 2018 one. 

I definitely recommend Scarlet Heart Ryeo, one of the best dramas I have watched!!! Also Sungkyunkwan Scandal fits your description and I really like it, it's fun! If you haven't seen You're Beautiful you should definitely try it ! It's similar to Boys over Flowers.

  • Moon Lovers
  • Atashinchi no Danshi
  • You're beautiful / ikemen desu ne
  • Ouran high School Host Club (the drama is a good adaptation but I also recommend the anime)
  • Hana Kimi

Anime:

  • Fushigi Yugi

I've made a custom list called Harem in Reverse. Other recommendations are welcome!

I made the tag here is everything mdl has with reverse-Harem

https://mydramalist.com/search?adv=titles&ty=68,77,83,86&th=1621&so=relevance 

Because I only watch japanese so mine would be :

Hana yori Dango, (and all remakes)
Ooku  (drama special with nino)
Hanazakari no Kimitachi e 
Ouran High School Host Club 
Hajimete Koi wo Shita Hi ni Yomu Hanashi 

Honey and clover both the movie and the drama could be categorized as this but it is a friendship movie and not a romance film though the boys want more.