Sir this: https://kinkytranslations.com/your-rival-in-love-gets-prettier-every-day/ ( The MC and MLs can participate in a long gay parade. )
It's a webnovel, but no manhwa. Title: Transmigrated into a Female-Oriented Card Game
Ch 1-9: https://www.scribblehub.com/read/436595-transmigrated-into-a-femaleoriented-card-game/chapter/436600/
Ch 10-rest:
https://shanghaifantasy.com/novel/transmigrated-into-a-female-oriented-card-game/
Is there any gay harem manga?.No straight couples.Preferabaly more than 3 gay mens