He added: “And Tony started as the brash billionaire playboy, and the stakes are growing for him, the responsibility’s growing for him.
“We realized at one point, late in 2015, that for Steve to be his best self, he was going to have to get a life and for Tony to be his best self, he might have to lose his.”
On why Tony Stark had to actually die and not just retire, the writers said that it would always mean the possibility of Iron Man 4.
And as much as some fans would want that, sometimes it’s good to quit while you’re ahead.
source: express.co.uk