Disclaimer: I do not own Ouran High Host Club. All characters belong to Bisco Hatori.
Tamaki knows that Kyoya is using him. But he doesn't mind. He was the one who had brought the Shadow King to the surface. And it has worked out pretty well. With Kyoya running things from behind, Tamaki is free to focus on what he wants to do. After all, he knows he need only control Kyoya to control the world.
Tamaki knows Hikaru and Kaoru treat him as entertainment. They purposely tease him for their own amusement, wanting to see his exaggerated reactions. He obliges them willingly, behaving like a complete idiot for their sake, because he wants to teach them how large the world is. Two against the world is lonely, no matter what they think.
Tamaki knows Hani is in the club for his selfish needs. If he wanted to, he could beat his family into submission. But the Host Club is a convenient excuse for him to love sweets and fluffy things without taking responsibility. After all, everyone says it was Tamaki who told Hani to be true to himself. No one ever asks what would have happened if Hani had decided he didn't want to listen anymore. And that is how things shall always be.
Tamaki knows that Mori stays with them only because of Hani. That is why he does nothing beyond what is necessary. His silent composure is simply because he puts in so little effort. He is here to fulfill his duty to Hani. He will treat the ladies kindly for Hani's sake and no more. That is why Tamaki holds onto Hani even harder, for if he loses that one, he will lose them both.
Tamaki does not know he loves Haruhi. That is the one fact he will not acknowledge. He has worked hard to make this family and this is the one thing that could destroy it. So he hides that love under fatherly affections, lying to everyone but most of all to himself. Yet one day he must face the truth, and what he decides then will either make everything worth the while or come to naught.