[ Giorno had one reason why he was apologizing but then when Fugo drops the small bomb of him indeed being the new boss, the perspective suddenly changes. He had been apologizing for the fact that Fugo was sheltering the weight of knowing things that Giorno didn't when they should both be carrying the weight...sharing the burden of whatever they could.

But if he was the new boss and if Fugo had sworn himself to him and his dream—he truly was apologetic. Apologetic but not in despair. Instead he'll look to Fugo and sort of understand what must have happened. The deaths of Buccellati and the others... He lost true friends and allies on the first major stepping stone in achieving his dream. ]

So I've become the boss. [ Don of Passione. Don Giovanna? Boss Giovanna? None of those sounded right to him. But what had Fugo called him that one time? Giogio? ]

Fugo... I'm glad that you're here with me. [ Because in the end, Giorno could have stayed in the dark and not known anything. ] For you, who sees things to clearly and is careful, to side with me and my dream—I'm honored. I will make sure that I am that boss you swore an oath to.

[ After all, just because he was told he was the boss it didn't mean he had earned it yet. ]