Regarding Takeo's feelings for Ao, I don't think he ever liked Ao romantically - not that anything would be wrong if he did. IMO it was Takeo seeing how serious Ao and Shingo were about each other that he realized he could seriously date men as well, that it's no different than seriously dating women. Up until then he only ever dated women and had never even considered men as an option. And this is shown when Wako asks if there's a particular reason for why Takeo can see himself dating men in the future, Takeo says, "Well, not really. It could be a man, it could be a woman, it could be anyone no matter where they come from. When you love someone you think about that person more than anything else. And that person will be the most precious to you. I don't want to miss out on something that could grow into a life long love."
He keeps talking about putting the one you love first above everyone else because this is what he witnessed between with Ao and Shingo during the whole thunderstorm drama in the previous book. Honestly, I think that he's taking relationships and love more seriously because he saw how serious those two are because it sounds like he never took it seriously until then. ALSO there would be no reason for Takeo to lie when he was asked again if he had liked someone that changed his mind into dating guys in ch. 5-6 if that was the case lol