You should know what you're getting yourself into when you click the title with a tag "ra**". Don't take this lightly and then come whining in comments.
This is a violent example of lovers to enemies to lovers (i guess?). Fl is smart but too pure to be a spy, she believes her fiancé will never let her get hurt by enemy, but her morals will quickly be smashed by reality and captain's di**, ofc. He is clearly in love with her since early childhood, and since then has asexual problems, surprise: he is hard only for her. But her mother was famous for seducing and killing men, like his father, so his hatred for women made him a complete monster. Cute couple they make.

Why do I like stories like these, you'll ask? Ra** is ra**, but when there's love involved it's a whole different kind of tragedy (still ra** though). So I'm curious how they will heal their souls, overcome traumas and come to love each other freely. It's such a difficult task to lead such a story to happy end with grace.
Good luck to author. At this point it's good in art and story.

(I'm counting on captain to turn traitor just for her, looove this trope)