I would understand the FL reasoning if the ML form her perspective was in some way romantic or showing interest in the Saintess. But from every angle he doesn't seem interested and is only showing intrest in the FL. When Fl's are this blantly dense I get irritated and bored because nothing of note is really happening just trope after trope. ( ̄へ ̄)
Even the ML himself doesn't think he's in love with her (typical emotionally-stunted- from-a-young-age-due-to-difficult-life behavior). But the FL is biased based on her memories of the novel. And the ml should have made his stance clear when EVERYONE thought he favored the concubine due to his behavior.
This is so funny for some reason. The moment I try and put the plot in focus it just becomes nonsense. Like within the same chapter he went from hating it to loving it . JUST WILD