My guess is that what the Dolphins are asking Ramsey to due schematically (and where the team is at competitively) just isn't exactly what's best for Ramsey the DB.
I think elite players want to win more than anything else. Hill's explosion at the end of the NYJ game last year was pure frustration IMHO...a down year, playing through injury, your QB in/out of the lineup, eliminated from any real shot at contention pretty early.
I find that totally understandable considering that Hill spent 3 years in Miami watching his former team go to 3 straight Super Bowls while dealing with tons of setbacks on his new team: defensive injuries, OL injuries, QB concussions, etc.
I suspect that Ramsey is in a slightly different situation where what the Dolphins need out of their best CB just isn't what's best for Ramsey the player. I'd bet he simply doesn't want to get stuck plugging a hole (at his age) on a team that's perceived as rebuilding.
He's not capable of doing all the heavy lifting and needs to be supported by young, athletic players rather than being the elite player himself. He's at an age where his football IQ needs to be what he's selling.
In Miami, the lack of overall CB talent forces Ramsey to plug a hole, stuck on the boundary where he occasionally gets exposed...which I'm sure he probably hates.
I suspect Ramsey will end up somewhere he thinks he can reach the Super Bowl and where the talent around him offsets his age allowing him to be a more versatile player, rather than merely an aging boundary guy increasingly at risk of being exposed.