From what I remember, the uke's family was something like a shaman. His sister was supposed to marry the sick son but ended up running away. Uke has no choice but to disguise himself as his sister and get married to the Wealthy family's sick son. Then the Seme was his BIL, he found out uke was a guy. They kinda get into some sexual relationship until the uke fell in love with him.
I just really can't understand this kind of bullshit plots. Blaming your kid then adoring a kid that isn't even related to you. Both father and brother are totally trash! That bitch fake sister is also annoying. I don't want them to die easily, if possible I want to see their end full of regret, humiliation and suffering. It makes me furious after seeing some spoilers that both father and brother were not sorry until the end. Total trash.