Wade said Friday that he could just tell from James' body language during a flight from Las Vegas that he would not be coming back.
"Yeah, I went to sleep knowing," Wade told reporters. "He called me the next day. But I knew then. Obviously he still had to say the final yay or nay, but I knew. I could tell."
It'll be up to Wade, Chris Bosh and a new support group that includes free-agent acquisitions Luol Deng, Josh McRoberts and Danny Granger to try to extend the Heat's run of consecutive NBA Finals appearances to five. With James, Miami won two titles in four seasons.
"As his friend, I'm just supportive," Wade said. "As crazy as that might sound, I'm supportive of my friends doing what makes them happy. Obviously, same thing with him in this situation. You've gotta do what makes you happy -- selfishly do what makes you happy. The decision to go back home was that."
Wade said he did not make any pitches to get James to stay.
"It was a different summer for us," Wade said. "It's no secret, obviously; it's been a change in how we looked the last four years by losing LeBron to Cleveland. I think our ownership has done a great job so far of trying to not replace but recover from that. The only thing we do as a franchise and as players is we move forward."