Cain, if you don't need the demon lord then give him to me please!
The netizens are literally what people are like in real life.
I feel like I know Akane from somewhere....Oh yeah right! I saw him in mirror! Pulled an all-nighter to binge-watch BTS videos shamelessly. Yeah definitely Akane. I'm obsessed with good looking faces!!!
She should just tell him the truth. It would be much more convenient and I don't think there'll be any losses. He's not the kind of person who'll advertise it to the whole world anyway. I don't know why characters keep things secret when it would be much better to just spill it. It just creates more problems and misunderstanding that normally takes 50+ chapters and 10+ liters of tears to solve.
But you see, the FL is not omniscient like the readers. We know what the Duke is thinking during scenes, but the FL does not. All she knows about Duke is that he sacrificed himself for Abel, and that he's cold to others who is not his son. I think being cautious on her part is understandable. It's not a harmful secret anyways, I think it's just a part of the plot the author made to show us how the ML gets jealous or how the ML would be surprised that FL is more awesome than he thought.