Why did he die?
It’s not okay.
It’s better than if Alexander had died first, though. Because then Hephastion would have had to witness as the Diadochi tearing Alexander’s empire apart. And he would have been sucked into the chaos and then one day he would have rode into battle on Bucephalas (who obviously didn’t die, and who obviously could only be ridden by one person other than Alexander and that person would have been Hephastion), and for a moment everyone would have looked at him and seen Alexander. And then they’d have fought and killed him even though in their hearts they knew that would have been the last thing Alexander wanted.
Oh, god, why did Hephastion and Alexander not just die side by side in battle.
Or live forever.
Or walk into the desert and turn into birds.
It happens, okay.
I believe it. They did turn into birds.
And have been reborn numerous times since. Finding each other through time and space.
They live forever.