"I'm on the run, Tony," he answers. "They passed a law, ratified by the UN. Unanimous vote - people with superhuman abilities and weapons such as the Iron Man armor have to be under a register. They have to vote everytime we wanna leave US soil to do a mission. I couldn't stand for that, so I left."

Well, he blew up a lot of stuff on his way out, like his friendship.

"Tony... he wanted to keep the team together." Not to mention, repair his relationship with Pepper. Steve had been supportive of that, he'd understood. But - he just couldn't do it, ultimately.