I honestly have zero doubt that when LeBron signed in 2014, he intended to stay in Cleveland the rest of his career.
Then Durant decided to be a coward and sign with the Warriors and Kyrie forced his way out and now maybe he doesn't see a path (I'm not sure if I do either tbh) for the Cavs to compete with Golden State. Thompson and JR got injured and declined so fast and there's money tied up there, the Kyrie return is awful, and the only hope is the currently 8th overall Nets pick somehow being higher. The roster is full of overpaid (which is fine, they won a title, but it limits flexibility now) mismatched (thanks bad GM Dan Gilbert) parts that can't compete with the Warriors.
And LeBron is exhausted. And it's February, and if the Cavs don't make a trade, not sure LeBron can carry this bad of a team to the Finals. So why would he stay?
tl;dnr, LeBron didn't want to leave but probably will, because of some things outside the Cavs control (KD cowardice) and totally botching last summer (Gilbert's ego).
The Warriors blew a 3-1 lead in the NBA Finals with the unanimous MVP.