Time is a circle. This is not a new concept for you, you watch too much sci-fi for that, but it is not something you have ever had to think about before. And now you are having to think about it a lot, because you have just ran into the consequences of breaking the circle.
It makes sense, really, when you think about it. Because if you'd saved him, he would have been alive, and then you wouldn't have saved him and then he would be dead and then you would go back and save him… But you weren't thinking then. You were watching and you were acting, at the same time. And now, in trying to save one life, you have doomed many.
You are ashamed and scared, but you are too stubborn to admit it. You don't want him to think of you like that, and besides, you have not earned the right to be scared. You are the cause of this. You must accept the time that has gone by.
He is braver than you, you realize; he is willing to sacrifice himself, when you were not. But even knowing as you did of the circle, you still said goodbye to him. Even if he is dead, you want him to remember you.