read up to ch 21 - I paid for all the chapters so you don't have to

the ml is just insufferable. back when the ml and Alicia were in the prison, the ml felt hopeless and traumatized from hearing his comrades screaming and dying for him in prison. He asked fl how to escape from the nighmares of his comrades screams and guilt. fl gave him a handerchief with Lily of the valley embroidered on it and tell him to think of meaning of Lily of the valley, which means hope and return to happiness, and how if he feels bad for his comrades, then he isn't a bad person and if she were his comrade, she wouldn't feel bad for sacrificing her life for him.
Then fast forward to the present. ML summons her to his room and corners fl and asks her what is her favorite flower. she said 3 different flower names and the ML pressed even harder for her favorite one and fl said lily of valley. ML goes crazy and kisses her without consent. btw, the reason why he summoned her is to tell her to stop talking to me, especially Chase because Chase proposed to fl and he saw it.
Also, the betch of a sister knows FL has the healing power that only her family can have. and each generation only has one person who has the healing power. ML is also suspicious of her not being his "savior".
Chase is the best guy. There is no way making ML the fl's love interest will be a good idea when the author spent the whole manga developing the plotline for Chase.

I will say, that the story is well written and the betch of a sister is not like a comically badly written villain.