Murray, who will face Australian Matthew Ebden after receiving a first-round bye, offered few clues as to why he and Lendl had split when addressing a news conference on Thursday, although he reiterated that it had been a mutual decision.
"We sat down Saturday evening. We went and had dinner," said Murray. "We chatted for an hour about other stuff, and then we chatted about us moving forward," Murray, who has struggled for form since returning from back surgery, said.
"That wasn't something that happened after Indian Wells. We planned to sit down when I got to Miami to discuss moving forward. It wasn't going to happen.
"The best thing to do was just to move on."
Scot Murray had been tennis's nearly man until hiring former world number one Lendl in December 2011, losing in his first four grand slam finals.
In his first year with Lendl in his corner Murray reached his first Wimbledon final, won the 2012 Olympic gold medal and then became Britain's first male grand slam champion for 76 years by triumphing at the U.S. Open against Novak Djokovic.
Last year he ended Britain's 77-year wait for a men's singles champion at Wimbledon, again beating Djokovic.
"It's a tough one for me because he's been a big part of my life," Murray said. "He's been a big part of my team. He made a huge difference to my tennis."
Murray has not won a title since Wimbledon, although he missed the final two months of last season because of back surgery. He was beaten by Roger Federer in the quarter-finals of the Australian Open and last week in Indian Wells fell in the fourth round to big-serving Canadian Milos Raonic.
Having gone long stretches of his career without a coach, Murray will take some time to consider his next move, although he said replacing Lendl would be tough.
"The thing that he was brought in to do was to help me get over the line in the big events, and that's what he did," said Murray. "My game was kind of there. It was the mental side in dealing with pressure situations that he was there to help with.
"That was the biggest influence he had on my game.
"So very hard person to replace, you know. You can't replace that sort of experience easily."
When Murray and Lendl joined forces it seemed to spark a trend of players hiring former greats with Djokovic turning to Boris Becker, Federer hooking up with Stefan Edberg and Maria Sharapova giving Jimmy Connors a brief try.
Murray offered no hint as to whether he might turn to a former playing great again for inspiration and guidance, only that for the moment he planned to enjoy his time off the leash.
"It's not going to change drastically the next few weeks," said Murray. "But I'm finished with Davis Cup, then I will sit down and have a think what I want to do with that situation and how I want to move forward with it.
"Sometimes being a little bit freer on the court can help for a few weeks.
"I think in the long term it's better to have, you know, someone there and having a structure and a plan as to how you're going to move forward and how you're going to improve.
"Certainly for a few weeks it can help sometimes."