Since Leona realized that darling is his darling and the fact he respects women, would he apologize to her sister-in-law for trying to claim her as his darling? The more I think about it the more unlikely I see him directly apologizing to Falena.
Also, if a yandere plublicy said that a darling is his darling(like "I claim them, we are soon to be married" delucional final boss) but the darling plublicy dislikes the yandere and doesn't even live with them(but they remain unclaimed). Then how is that viewed in different cultures?
Sorry for the span notes, I just love your AU so much even if the boys stress me so much, everytime they torment darling I'm like that meme "Get a job!, Get away from her!"
After losing a fight to his brother٫ Leona was already forced to formally apologize to the both of them (even if he didn't mean it). Since then٫ he's mainly avoided seeing them٫ especially together٫ to avoid that feeling eating away at him. After meeting Darling٫ though٫ he actually grew more noticeably willing to be around them. He's too embarrassed give an actually apology now٫ but the intent is definitely noticed. Leona does still care for his sister-in-law٫ but in a more platonic way now; she's also the one he'd be most comfortable talking about his true darling with. Both her and Falena have already long since forgave him٫ and were very happy to have Leona's presence around more. His sister-in-law always thought of Leona as a cute younger brother.
A darling is considered unclaimed in any culture until relocated by their yandere. Even while considered unclaimed٫ the yan is typically still seen as in charge of watching over the darling.