
Like loosing power? I mean, it seems like he stated that he never really loved her. It was a way to get his sister anyways. That is what it seemed like to me. Since he never loved her, I don’t see why he all of a sudden cared, unless he has a serious case of FOMO (fear of missing out) hahaha! (๑>◡<๑)

i dont think they specified on who he was blushing for when they were young, but if it was the legitimate daughter then maybe he remembered those times when they first met and the first days of their happy marriage and regretted that he tooke her for granted (if he loved her then why did he get together with her sister? idk i think the demeanor and noble pride of a "legitimate" daughter got to him and he got tired of it, in ch. 53 he said acting reserved like a proper main daughter, sitting on ur pedestal and compared her to the concubine born who he claims to be ernest, which she's not... i think that's when he started losing it, they have diff backgrounds the guy was poor and the girl was well.. legitimate and he thought that she wouldnt understand him and he wanted someone to, and idk ig he wanted smth to spice his life and the concubine born was desperate enough to indulge him-seducing him n pretending to care about him n shit, and this was what the guy wanted-needed and just falling into the hole of thinking he really loves the cb (him saying that he didnt have a choice bc he was poor) and the separation just reminded him of his love for the main wife).
if he did love the cb ever since they were young.. then he dumb *keyboard smash*. but ig yeah he already got used to her and like @Thiwzil said, fear of missing out- and ego. like when someone keeps pursuing a person but then that someone eventually got tired and stop, the person suddenly pulls her back.. yeah like that. and ig power too? he did hesitate when the wife asked him if cb will be the main after she's gone
that's all pls dont hate me, i really dont have anything better to do ><

Thank you. This makes sense. When people get bored and don’t communicate their needs things happen. People cheat and it sucks. In any case it’s fortunate that the mom left. This man belittle their relationship and refused to really try to get to know his own wife and daughter. He didn’t express his needs and saw something new and exciting in his sister-in-law and had another baby, he hid this truth and continued to belittle his family, only keeping it for powers sake and only divorced when it became too aggravating to keep. He settled for power and got upset with the rules and customs that come with it.

Her dad had feelings for the sister since the start. He just didn't marry the sister because the sister was the daughter of a concubine and he was a dude trying to move up the social ladder. It was better for his reputation to marry the main daughter (FL's mom), so he married the older sister and had an affair with the younger sister. That, and he mentioned something about their mother interfering with the marriages.
Wait, why does he regret her leaving? I don’t get it.