It's not a curtain, so not sure if it counts but...
4. Senior Secret Love: Puppy Honey 2 - Rome (ML) and another guy are in a tent. Rome leans in to check if there is an eyelash stuck in the other guy's eye. Rome's love interest (the other ML, Pick) sees from outside and mistakenly think they kiss since it looked that way from thier shadows.
NoirRoseHeart:It's not a curtain, so not sure if it counts but...
4. Senior Secret Love: Puppy Honey 2 - Rome (ML) and another guy are in a tent. Rome leans in to check if there is an eyelash stuck in the other guy's eye. Rome's love interest (the other ML, Pick) sees from outside and mistakenly think they kiss since it looked that way from thier shadows.
I count everything that looks like a hug inside a closed room/area then. Seems like I choose a hard question. I just like that kind of scene. Shadow behind the curtain with love rival saw them. Makes my heart beat faster.
5. Story of Kunning Palace, does it count ? as ML kiss FL in the carriage, behind the curtain of carriage, and it is her father who saw them kissing
https://www.youtube.com/watch?v=qh8PM2ld49Q
3. Perfect Propose (Mc is an overworked salaryman. He's being gaslighted by his bos into thinking he's bad at his work until the day his manager, who's about to quit, tell him the fact and advise him to also quit but no, he's promoted to become the new manager. He only has work, no life, no lover, no crush, no friend before ml appears and tell mc he wants to live with mc)
Remember another one:
4. Doku Koi: Doku mo Sugireba Koi to Naru
(Mc is an unmatched lawyer, only losing one case during his whole carreer and that's because his partner betrayed him and in the end works for the other party's company. He only has works and plants, he gives all his potted plants names ^^ and talk to them. That until ml appears wanting to be his partner (his plants love ml) becase mc annoyed another partner and no one else want to become his partner)
5. She and Her Perfect Husband FL is an amazing attorney but cannot keep house nor cook for herself. Mainly, she just focuses on work. To keep her job, she enters a contract relationship with her "perfect husband" who keeps house, cooks, is smart and supports her career endeavors.