[ Not once has Luffy ever blamed Ace for his decision. Throughout that whole journey to save him, the only thing he was focused on was finding a way to reach Ace in time. Even after the reality set in that he had failed, and his brother was lost for good, Luffy's always attributed that to his own lack of strength. ]

No, Ace, it's because I wasn't strong enough ...! [ If he had been, he would have made it. ] I went there to save you, but in the end, it was you who had to save me!

[ And how can he protect anyone, his own crew or the friends he's made, when he's still too weak? That's the kind of thought that was on Luffy's mind two years ago, and why he decided to put the journey on hold. If he had stayed at his level then, he would only lose more people. ]