Brother In Law
This story was just shock after shock. In the beginning I thought Sanghyun was pursuing Leejoon while already engaged with his sister but no, he met Leejoon first and they started dating. Some moments were just unbelievable. Like how Sanghyun told the sister of his feelings for her brother so he can't marry her, but she just said if they were not dating, then it doesn't matter. Also, the fact my guy was taking advantage Leejoon when he was "sleeping" while wearing a couple's pyjama with his wife and beeing caught her doing so. I thought Sanghyun was a complete manipulative, cheating psycho at the beginning of the story, but when reading the whole thing, I feel like everyone was a little toxic. But Leejoon really was a victim in this whole situation. It must have been hard for him to find out his boyfriend was going to become his brother in law out of the blue. Anyway the story had a situation that was interesting and new to me, so it was kinda enjoyable.
Shin'yuu to Gouri Teki ni Yaru Houhou