This is ridiculous. Philia clearly loved Ars. How could someone like that stay with his piece of shit father, who wanted to kill Ars and kept calling him "defective"? It clearly wasn't that she was forced to stay, since her interactions with him looked like she genuinely enjoyed them.
And after being tortured for 10 years, Ars just left? No revenge? Let me guess, an extremely edgy plot where the author includes mature themes like rape or torture, but the protagonist responds to everything like a shōnen protagonist and can't kill anyone? Of course, his inability to kill will have some kind of ass-pull explanation like "mommy asked me to be good" or some shit like that.